Here's a good explanation: http://www.ccheever.com/blog/?p=10 http://www.ccheever.com/blog/?p=10 FBML allows you to do specific Facebook-only features easily,

Here's a good explanation: http://www.ccheever.com/blog/?p=10 http://www.ccheever.com/blog/?p=10 FBML allows you to do specific Facebook-only features easily, like friend requests and searching for your friends. It also has documentation and tutorials, which is not trivial when making the FBML/iframe decision.