Not in any great detail, no. Enyo has specifically been announced in the press release, "along with a plan for the remaining components of the user space".

Personally I would be very very interested in seeing the service side code opened, so I can finally use the "cloud"y features of the OS on my terms.

Obviously things like GL drivers and such to which HP don't own the rights won't be opened. It does look like they want people to run this on real hardware (as opposed to emulators on a PC) though: they're having a new touchpad sale to give out all remaining stock, and they just released WebOS 2.2 for the Pre 2, something they have very explicitly said wouldn't happen before.

There's a lot of information missing right now, but I remain cautiously optimistic ;-)

Edit: some more info here. Read the whole thing, sounds like they really mean it.