But because the issue was raised, I was thinking there was maybe some new instruction Pieman. Sometimes the policy gets adjusted and tweaked ahead of the manuals.
No, there is nothing new.
The policy for vectors has always been (as is listed in the Illustrator's manual)
DO NOT Use text as the primary focal point in your image
This also applies to completely hand drawn fonts that do not at all resemble copyrighted fonts (other than they are obviously alphabetical characters, of course).
This means that vector contributors at istock are not allowed, for instance, to design a calendar page with completely original illustration and typography. They are not allowed to illustrate letterforms and sell those individually or as a set.
However, on the raster side, they are ringing up thousands and thousands of sales with things like this:
example 1and this:
example 2and this:
example 3A few lucky souls have managed to slip through the very profitable cracks:
http://www.istockphoto.com/file_search.php?action=file&lightboxID=3815234