Support for GIFs has been a highly requested feature, and adding it in makes reading through a Twitter feed much simpler, as you won't have to open up a new window every time you want to view one. Notably, Facebook has adamantly refused to add support for GIFs, seemingly over concerns of how it would make its News Feed look. They may not all be beautiful, but Twitter seems to get that they're all fun.
This is a GIF. http://t.co/THNS5CtxzA— The Verge (@verge) June 18, 2014
Long overdue, imo