There will not be level-scaled dungeons in Skyrim... in the sense that they get scaled to your level no matter what. (ala, Oblivion)
As been mentioned several times in this thread, and is worth mentioning again, they will be more or less random.... which is a very, very good thing when it comes to the sense of exploration.
Say that you're level 1 standing in the woods. There's a dungeon on the left, one straight ahead, and one on your right. The one of your left could be a lv 1 - 4 dungeon. The one straight ahead could be lv 30 - 35. The one on the right could be lv 16 - 20.
If you go into the left dungeon, it will lock at level 1, and you'll encounter things you can handle. If you go into the dungeon straight ahead, it will lock at level 30, and you will get your ass kicked. Come back later.
If you return when you're level 28 and go back into the dungeon on the left, it will still be inhabited by rats and other level 1 things. If you go back into the center dungeon, it will still be level 30 and now you'd have a fighting chance. If you decide to pop into the dungeon on the right, it will lock at level 20, and you'll probably be able to plow through it with a few cuts and bruises.
So as you can see, dungeons will not scale to you in the purest sense. They'll only scale within their predefined ranges, depending on what level you are at the time you enter then, at which point they'll lock at that level forever... or until you open the console and type in some command to change it manually
There was a huge thread all about how the dungeons will work, and that's what I remember from it. No telling if everyone's understanding is 100% accurate, but we'll find out eventually.