Schtock is meant to be the visual blog of someone who works for a large photo library. Here's the about page
Who describes themselves as an "amateur designer"? The about text seems contrived and smells of a marketing cover up. The actual artworks are nice and designy. The type of stuff you see on FFFFound.
The Denver Egotist seems to have deduced that it's Corbis. So is this an official promotion or really just someone doing it for fun. If this was indeed someone just mucking around they spent longer on the HTML setup of the site than the actual designs. A Flickr account or simple blog template would have worked better for someone just mucking about. They also would not have registered the domain via a private register either.
If it is Corbis they are now in the awkward position that if they do admit they are behind it they look stupid for trying to fool us. This is sad as the idea behind the site is solid just the way they tried to sell it to the world is sloppy.
Getty Images also have a blog. 4 in fact. but they all seem to have little readership.