The last couple of days I wrote a Zend_Bittorrent_Torrent class that is able to create torrent files like btmakemetafile. I have added some info about it to the proposal I have for a Bittorrent component to the Zend Framework. I have also written a lot of unit tests for the component which have been a nice experience.
So if anyone reading this have any interest in such a component, don’t hesitate to give a comment or two. :)