The server-side modification file for Apache to enable Transporrent has been posted (before it even went into svn, hmm perhaps a bit backwards). Also, there is an extra document which explains a bit better what needs to be downloaded to make Transporrent work. It mentions an .xpi file and a php manager, neither of which are posted, but are on their way...
So at this point Transporrent is a concept -- to make 'normal' http file downloads take advantage of the benefits of BitTorrent, without user intervention. It turns out the implementation is quite simple. The 'tough' part is the chicken-and-egg problem, because both client and server need to enable Transporrent. Check out the Transporrent overview doc, and the soon-to-be uploaded prototype.