The current implementation is of draft-04
It is serial 005 006 cset 351fc42a655 c9397376c6b3 on try
source is at
https://tbpl.mozilla.org/?tree=Try&rev=351fc42a6557c9397376c6b3
Builds for windows, os x, and linux are at
http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/mcmanus@ducksong.com-351fc42c9397376c6b3/
feedback of any sort welcomed to pmcmanus@mozilla.com