What are the new birds in Angry Birds Space and what are their abilities?
Angry Birds Nest has a post with analysis of the announcement video:
This seems to be accurate based on this newer post describing all of the birds in detail, which I won't reproduce.
Edit: Based on playing the game just now, it appears that the blue birds don't speed up as mentioned in the latter post (but not the first). Possibly it was just confirmation bias on ABN's part since there's a nice rocket-like glow when they split apart. As well, all birds show a plot of the first part of their trajectory.