Official Bitly plugin for WordPress. Replaces shared links with Bitly short URLs. Also, gives you the option of placing a Bitly widget on your site.
We have tested it on the following sharing tools: Wordpress Jetpack, ShareThis, Facebook (official facebook plugin), Really simple Facebook Twitter Share
We also tested it on the following themes: Twenty Twelve, Twenty Eleven, Annotum Base, ButterCream, Custom Community, Esquire, Montezuma, Patchwork, Pinboard, Presswork, Responsive, Spun
Posts that were created prior to installing the plugin will only get a bitly short link when someone actually visits the old post. This will result in old posts showing up in your public bitly bitmark stream (https://bitly.com/u/BITLYUSERNAME) unless you have set your default bitmark privacy settings to "Private" at https://bitly.com/a/settings/saving