Facebook application developers who already know PHP can be happy about a recent announcement on their blog - the introduction of PHPEmbed library into their setup (as well as a release of it out to the public).
In order to make embedding PHP truly simple for all of our developers we developed the PHPEmbed library which is just a more accessible and simplified API built on top of the PHP SAPI. The library is so useful, we decided to share it with the world. Check it out for yourself at http://developers.facebook.com/phpembed/
The library (currently in release 20070924) can be grabbed either directly from their download link or via the public svn repository they've set up. There's also some documentation and help for it in the form of a developer's group and the manual (PDF/HTML).