In additional to launching on the App Store Color Labs also purchased the domain color.com for a reported $350,000 where it has staked its virtual claim. (Update: It bought colour.com too, price TBD).
The app's concept is ridiculously simple, and probably best described by the simple description on the App Store:
I'm a fan of Instagram, so I'll give it a shot. Although the reviews are mixed in the App Store, the app's been out less than 24 hours and we need to give it some time to mature. Besides some nitwits don't read the requirements then give apps one-star ratings, because they can't read.
An Android version of Color is also available.
Update: I agree with Lockergnome's Kelley Clay, Color could be a little creepy. Check the fella in the first screenshot on their App Store page. Color might want to replace that shot -- if it expects to get any female users whatsoever.