Hmm... personally my respect for the guys who made Box2d has shot down. If you want credit in games that use your tech, make that a requirement of the license; if you don't do that, don't whine when people use it without crediting. As for Chillingo: well, publishers in general take far, far too much credit for games so I think its kinda nice to a studio not making a big deal out of it.
If he would have asked nicely Im sure Rovio would have gladly include his name, after all they used the engine. But stabbing them in the back like that... lame, what an ass. There are tons of box2d games, and none even compared to the success of angry bird. You think only gameplay that makes the game? The charm of the characters, great game design, all play an equal if not more part than gameplay alone or the engine behind it. So do a better marketing job yourself that doesnt involve backstabbing legit developers. You can start by changing your own licensing terms.