Some subtle points that many of these 1-line posts here are missing:
1) Morrowind DID use levelscaling, sometimes quite annoyingly. Never noticed fire atronachs occuring near daedric ruins around levels 6-8? Blighted animals on roads at the same levels? Golden saints in the Grazelands around levels 15-20? The good thing about Morrowind's levelscaling is that most regions still had rather predictable enemies (Ascadian Isles, for example, never offered anything harder than a kagouti, and seriously, this is how it should be; the Grazelands, though, had lots of variety). Sorry, but Morrowind's botched up balancing has nothing to do with the presence or absence of levelscaling. Morrowind got boring after level 25 apparently because Bethesda didn't expect anybody to play that far beyound level 25, or because they had to publish the game quickly, or for another reason, but this is not related to levelscaling, absolutely. (Sphagne already pointed this out, but apparently not many listened.)
2) All of the TES games from Morrowind on (probably also the first two, but I don't know) have more than enough content to allow players a lot of freedom without levelscaling. Here is my
first idea about how to do this for Skyrim (but I'm just a level 15 player, so it's mostly just a guess): Make the Helgen-Riverwood-Whiterun-Falkreath area a place for levels 1-10, including some but not all caves (some caves should be significantly harder), then Markath, Ivarstead, Solitude for levels 11-20, and there is still a lot of the map I haven't seen that can fill the level 21-40 parts. Levels 41-60 should be reserved for seriously difficult caves, scripted encounters at the end of the mainquest, quest-related dream realms and the likes, and some particularly difficult places on the map (that are avoidable when you have to go from a town to another one; for example, the giant camps are such places).
3) Even if you think levelscaling is a good idea, scaling from zero is not. By scaling from zero, I mean a leveled list which, at level 1, spawns
nothing, and later spawns enemies. I encountered this at Orphan Rock (first it was empty, then 4 witches spawned; quite a difficult encounter!). The player shouldn't suddenly find himself unable to walk a path he has already trodden several times!
4) Skyrim doesn't use level locking - at least not with bandits. If you come back to a bandit camp after some levelups and more than 3 days of absence (the usual respawn time...), the enemies have rescaled, whether you killed them or not. http://elderscrolls.wikia.com/wiki/The_Elder_Scrolls_V:_Skyrim#Enemy_Leveling_System got it wrong.
5) One point being brought up is that levelscaling gives the player freedom in going whenever he wants. But there is an other side to the freedom coin: Levelscaling takes the player's freedom to raise the skills he wants. Every "wrong" skill (a skill the player won't use for fighting) puts him at disadvantage. More notably, it constantly forces me to pick only the most strategically reasonable perk when I level up. Maybe at level 25 I will be able to deviate from that, but right now I have to optimize or I risk dropping the ball. In a non-levelscaled game you would just delay your success if you pick bad perks; in Skyrim you evoke failure. I must say that the presence of some very good perks makes me indeed feel slightly stronger when leveling up (as opposed to Oblivion), but there is no real freedom for me in choosing them.
6) "Don't play on Master" is not an answer to "on Master I am getting weaker and weaker". Unbalanced is not the same as difficult. Think about it.