I must have been asleep at the wheel, again. Last Friday, the XBL 2.0 specification became a Last Call Working Draft.
I’m personally pleased to see the design behind the new <implementation/> element. It would mesh very nicely with my precondition/postcondition article of a few days ago. It would also be nice to have support for <xbl:script/>. I will probably spend an hour or so reading over the specification in closer detail this week, in particular trying to understand this public/private object stuff.