Facebook Lets App Developers Swap Content With Custom Tags

Facebook took a step today to increase the cross-pollination between the more than 40,000 social apps built on top of its platform . Those apps are written in Facebook Markup Language (FBML, it is Facebook's version of HTML). FBML has something called "tags" which call up Facebook content inside each app. Now app developers can add "custom tags" to expose their own content to other app developers, and thus spread it programmatically. Some examples include adding playlists from iLike to other apps, a badge from Causes, or a list of the most popular books from Visual Bookshelf.