It looks like twitter + images/screenshots, more or less. You can follow people, users can post text + maybe a screenshot, and there are comment threads about the posts/screenshots. I think what has the potential to be distinctive is the community that develops, rather than any particularly notable features. (That said, since on the web most features should arguably be community driven, this is probably just the core set of initial features.)

I think there is a lot of demand for a site that really facilitates developers meeting designers, but I'm not sure what format, and what interactions, make the most sense. I've been looking for a solution to this problem for a few years, and I haven't found anything really satisfying.