You're probably aware that Twitter began supporting animated GIFs via its web interface in mid-June. If so, you may also recall that Twitter's iOS client has picked up support for this popular file format a mere week later.
The feature isn't exclusive to the company's own mobile apps: Twitter soon after updated its API to let makers of third-party clients implement direct GIF sharing via pic.twitter.com links.
Tapbots' Tweetbot, one of the best Twitter clients for the Mac and iOS devices, does not officially recognize animated GIFs. That's why tapping a pic.twitter.com GIF link in Tweetbot for iPhone opens the detail view for the tweet itself rather than play the embedded animation inline.
This has been driving me nuts - but not anymore. As it turns out, Tapbots yesterday issued a maintenance update to Tweetbot for the iPhone and iPod touch which apparently adds support for animated GIFs via Twitter's pic.twitter.com links. Strangely enough, the official release notes make no mention of this nice little addition whatsoever...