You can now post GIFs on Facebook thanks to a work-around from Giphy.
Basically, Giphy (a search engine for GIFs), created a code that makes GIFs actually loop on Facebook. It works simply like posting a link to a video. Either copy paste the URL of the page for the GIF you've selected, or embed straight to Facebook from that page from the portion where it says "share GIF." It will look just like a video upload to your Facebook wall or Newsfeed, in that you'll see a play button on the embed. When you press play, presto! You have a GIF. The only stipulation is the URL must come from Giphy. But who cares, GIFs on Facebook are finally here. [Giphy]
Update: The excitement over Facebook GIFs seems to have crashed Giphy's site, so check the site later if you're still experiencing problems.