Do próprio Linus Torvalds:
"Então quais são as grandes mudanças?"
NOTHING. Absolutely nothing. Sure, we have the usual two thirds driver changes, and a lot of random fixes, but the point is that 3.0 is just about renumbering, we are very much not doing a KDE-4 or a Gnome-3 here. No breakage, no special scary new features, nothing at all like that. We've been doing time-based releases for many years now, this is in no way about features. If you want an excuse for the renumbering, you really should look at the time-based one ('20 years') instead.
( Fonte )