Well there's a level cap of 255, but nobody ever reaches it without cheating (lowering your skills temporarily) because once you max out your skills, you can't level anymore.
Unless you're using the console or other methods that aren't in the game per se, lowering your skills in oblivion isn't cheating. Drain/damage spells or going to prison for example isn't cheating. They're not bugs. They were there in morrowind (and they were much worse because of the unlimited training), beth knew about it and did nothing to change it not just for morrowind, but for a new game as well. As far as I'm concerned that makes it a feature, not an exploit.
And I find complaints about level caps useless. Level caps on their own are meaningless. It all depends on the level-up system used and I've seen nothing that indicates NV will use the same one as fallout 3. Even if it does, I'd much rather see them integrate stuff like active ability type perks than worry about a number that in and of itself adds nothing to my character. Neck snapping stealth kills would be a nice start.