However, that article is just rumour. I think it's more likely they made some apc-like cache/optimizer than a compiler.
http://www.facebook.com/note.php?note_id=280583813919&id=9445547199&...
And the conclusion that it will be open source is questionable. In such case, why would they made them sign NDAs?
It is under PHP license.
Domas intervention is also noticeable, since he probably knows what's going on.
Hehehe.
Domas
P.S. we have full hiphop dev support in our quest of running wikipedia on it.