Here is the info I learned from reading this article, which is mostly old news, with a couple of new screens, including one I really like (described below).
1. The Radiant Story feature activates some behind the scenes game mechanic when the PC enters each new area.
Todd Howard: "A good example is when you walk into a town, we can have it [the game] look for someone with a child. We can have that child kidnapped and put in a dungeon nearby, one that you missed for some reason." In other words, when the cell for the town loads, the child is removed from the town at that exact moment.
2. There is an opening sequence in a closed area.
"Once you've finished the opening sequence (an escape from your own execution...) you're free to explore the world as you wish." The converse of that indicates you are not free to explore the world until you have finished the opening sequence, which is logical.
3. Dragons can choose to fly away and come back, making them more challenging to defeat.
Todd Howard: In a lot of games, including ours, you're used to, 'here comes the person at you' and you're in a hallway or an open area. But this thing is a beast that can fly off quickly, go around a castle and come back around. Often you can lose them and spin around looking at the sky because you don't know where they're going to go. They have a lot of cool behaviors that make fighting each one interesting.
4. There are some badass helmets in this game.
One screen shows the PC (wearing a
5. Light magic (from staves at least) can stick to walls.
"Dovahkiin fires a globe of light from his staff, which sticks to a wall..."
6. Only possible to have relationships with certain NPCs - and "in some cases" marriage.
"...you'll be able to start relationships with certain NPCs. Howard confirms you'll be able to make friends, recruit companions and - in some cases - actually marry the game's buxom wenches. Bigamy? It'd be rude not to."
This suggests fewer NPCs available for marriage). Also there is the suggestion of a possibility to have more than one spouse.
7. DLC info
Todd Howard: I don't know what we're going to do yet, but we want to do something that costs a bit more but is going to be more of a complete package....we're thinking bigger than with Fallout 3.