iMore: Thou shalt have no brand before Twitter Rene Ritchie, nailin' it:
In a very real way, much of the brand identity now associated with Twitter came from those hard-working third-party developers. Indeed, much of it came from the Iconfactory and Twitterrific, including such fundamental things as the bird as mascot (see Ollie in the picture up top), and even the word "tweet".
We often look at that as a sign of how much Twitter gained from third parties. They may look at it as a sign of how dependent they were on third parties.