After giving their official blessing upon the Blackberry twitter app (developed by RIM), it looks as if Twitter has come to the conclusion that anointing RIM’s creation as the official app was a dumb idea after all (via Mashable).
continue to focus on what is best for users and we will work together to make sure that we are creating more opportunities for the ecosystem on the whole. We will also admit our mistakes when they are made and the Blackberry client should never have been labeled “official”. It has since been changed and you won’t see that language used with Twitter clients in the future. (Ryan Sarver of Twitter Development Talk)