I want to point out a couple things here, since there seem to be a lot of misconceptions. 1) UEFI is not the problem -- it's one specific feature called 'secure boot'; UEFI is a very good thing overall, so we should point out the bad part and not the awesome whole, 2) MS isn't requiring that secure boot be required, or even that they have a signing key for it -- they're purely requiring that it be on by default, 3) the reference implementation and all known shipping versions of secure boot have a switch to disable it if the user so chooses, so it's not much of a lock-in facility -- it could be in the future, but it's not now, and MS isn't making it into one.
That said, despite being a huge Windows fanboy, Windows 8 is seriously making me consider switching back to Linux. This sort of lock-down is terrible for everyone, most people just don't realize how bad it is.