I don't think this should really go in yet. The 2.1 code is still changing too rapidly. If we get to something that really is stable, works for the vast majority of people and 2.2 is still a long way off then we can think again about retrofitting it to 2.0. For the time being though, I think we have enough on our collective plate.
Also, parport brings some user-visible changes, some of them quite nasty (the lp1-becomes-lp0 feature for example). I don't think it's good to change these under people's feet - they ought really to be able to upgrade from any 2.0 kernel to any later 2.0 kernel and not have things break all over the shop.
p.