The VP will be made in Vorbis. No question about that because the engine supports it. I have never ever heard any news saying that the engine supports FLAC, and to be perfectly honest, I doubt it'd be even worth it to put FLAC support in the engine. FLAC is good for posting them outside of a VP, which will most likely happen.
Listening to the tracks through my DT770's (I haven't been able to find a better, more defined set of headphones, EVER, Thanks CP5670!) and I hear very very little difference between the level 7 OGG files and the level 2 FLAC files. FLAC does sound better, and has the ability to be decoded without loss, but the OGG format still sounds very very good. So honestly, I think that's probably how it's going to be. FLAC for the web archive, and OGG in the VP.