December '05 for me, and I can upload 2.5Mp images as well, although I never do, all of my stuff on SS is 8Mp or larger, apart from a couple of early ones from my trusty old 4Mp EOS 1D.
To me the hassle of downsizing the images is not worth it for multiple sites, and if you do it would decrease the number of repeat downloads you'd get I would think, as a purchaser is more likely to come back to your profile and look for a specific theme or style if they got a good high res image, rather than a 2.5 or 4Mp down sample.
Just my 2c though...