There is document in the Getty contributors site but I think you need to get a password to enter. It explains sistering according to Getty there.

I made my Flickr account private a couple of weeks ago, for fear of image theft. Heard a lot of stories. I generally have better images there than I do with my microstock images. In a dilemma about it. Don't know whether to make the images public, I hear that even if I uploaded the images at 500 pixels, there are still programs which can make decent prints from this. Anyone, got any information on this? Thanks. Sorry to steal your post melastmohican, well done by the way.

I also got an invitation and 10 files selected by Getty but two or three of the photos are already on micro. Of course I would disable them on micro and put them on Getty as RF, but the problem is that you cannot choose the license for your images, the editors do. And since I'm not sure I can mention anywhere to the editors that the photo was available as RF on micro, there's a risk they will be assigned a RM license.
What to do? No idea yet but I'll probably contact support before submitting.

As for similars, you can use photos from the same shooting session as long as the composition, angle, feeling, model's outfit/makeup/etc is different. Once you create your account, there's a guide available on similars (with examples) and you can also find it explained in the agreement.

Actually, after reading again on their site, this is what I found:

"Only you will know if the image or its Similar is subject to any active licenses, including those rights you may have granted when the image was part of Creative Commons. That means it is important that you are aware of your image histories so you can be certain that you really are able to grant us exclusive licensing rights. When we select an image that is or has in the past been made available under a Creative Commons license, we know that in order to protect exclusive, rights managed licensing, we can only select that image for royalty free licensing. We are working on ways for you to be able to alert us to image history, more information will be available as we progress. Until then, you will need to delete from the image prep tool any image we select for rights managed licensing if there is any chance that it may be subject to any active license."

So, briefly, I may disable the images from micro then submit them to Getty and hope they will select them as RF. In case they attach a RM license, I will have the option to delete them. Good to know.

Komar, I agree, I have no idea why they chose Flickr but I won't complain at all 
As for "downloaded for free", that's only for non-commercial use in case of a CC license. I believe Getty only chose Flickr images with a license attached, whether is CC or all rights reserved. For all my images I have the download option disabled, they're "all rights reserved" and the only way to grab them is to make a screen caption which will get you a 500x500 px maximum jpg at 72dpi, pretty useless in my opinion.

check out this post

One of the things Getty has changed recently is that if they selected one of your images on Flickr.....and you've already sold it elsewhere as royalty free.....then you can still submit it and simply remove it from other sites from this point forward.

That freed up about a dozen images for me that I removed from other sites and made exclusive with the Getty Flickr collection.

We'll see how it goes.....but 20% of a $80 to $350 sale seems a tad bit higher than the same percentage on a $10 sale elsewhere.

Bit of a conflict of interest for Getty, they own Istock and you could be deleting images from Istock so they can have them as RF on Getty.

David

I am a little bit surprised that microstock people patronize Flickr users exactly like stock photographers do them. There is much more variety on Flickr than in microstock which means there from bad snapshots to art and everything in between.

I think it's actually brilliant business move from Getty. They got exclusive access to one of the largest repository of images on internet and they can go and cherry pick there. At them same time many Flickr users has no experience selling photos so they would agree on any conditions given. Notice that there is no way to submit photos. Only Getty can select.

 I just spent some time browsing through their collection. There are some good images there. Most of them though seem to be really overprocessed  - from blurs and color oversaturation to really darkening the image by screwing up the histogram. Which in some cases does achieve some dramatic effect. However, I don't think quality is even a consideration here, at least in traditional sense. It looks like the entire collection is about this darkened oversaturated oversharpened look which I heard is quite in vogue right now. So, some advice for people who want their photos choosen - move levels sliders way over to the right, same with saturation, apply even more dark around the corner of the image, them apply and blend in about 5 layers of gaussian blur and you have big chance to be selected! ;-)
I also saw quite a few classic microstock staples. And a lot of pet pictures, some of them a good, some ... well just pet pictures:)
Some stuff is plain weird. Not "wow weird", just ... strange. I am too lazy to post some here, there are some real "gems" over there , but you can always go enjoy them for yourselves:http://www.gettyimages.com/search/search.aspx/1/creative?brands=fkm,fkf,fks#

I remember a while ago big macros were trying to distinguish themselves from microstock by saying that they have good quality and micro stuff is crap. I guess it doesn't work anymore - quality standards on micro are ridiculously fierce, I wish the guys had some common sense and stopped this nonsense. But microstock quality is pretty good these days. So now the macros have to come up with something different - like stocking up some really creative shots and who cares about quality:)

It looks like what Getty is trying to do is to stock up some really unusual images - the price also makes sense, too - if you're looking for unusual, you should be prepared to pay a lot. Which makes sense, they have to offer something different to survive the competition with micros. Be prepared though, your quirky stuff may never sell, since there are not that many buyers that look for very unusual. On the other hand, if it just sits on flickr and not earning anything, it's much better to have it sitting on Getty:)

I wish microstock admins allowed more creative stuff in, why not have it - really dudes hard drive space is dirt cheap these days. And yes, a closeup of some guys's front in underpants with cooked spagetti stuffed into them (Creative (RF) #85153696 Flickr) is not going to sell as many times as one of Yuri's business teams, but again - why not have it? Maybe someone will need it someday, although really I can't imagine what for:)

May be they are trying to move on or as Chase Jarvis wrote, get more creative at post production:
 
http://blog.chasejarvis.com/blog/2009/02/scotts-guest-blog-creative-post.html

Sales via the Flickr Getty deal are starting to show up in contributor's account listings.  Most people (including me) are reporting one sale during the month of March (reported at the end of April).  However, the payoff is nice - I earned almost $80 on one RF sale.

Still very early to tell if this is going to take off, but if you're invited, it might be worth a bit of your time.

Out of curiosity: Are you only able to send them the pics they chose from Flickr also for the future? Or can you upload to them more, once they want some of your Flickr stuff?

It's by invitation only, and you have to list an image there exclusively for two years. You can list images as RF or RM.