Things I can confirm from my numerous views of the skyrim vids and net-trawling,
1. Insects such as bees, butterflies, moths, etc are harvestable.
2. Spells can only be used one way (Ray, Trap, bolt), the same spell can't be used all three ways as the early reviews seemed to indicate.
3. Spells with jump effects like chain lightning are confirmed.
4. Dragon shouts of slow time, ethereal form, burst of speed, dragon call, ice form, unrelenting force, fire breath, storm call, confirmed.
5. Technically the system is tri-wield, not dual wield. You can have something equipped in either hand AND a dragon shout ready go at the same time.
6. Items like webs can be cut with sword slashes.
7. Conjuring undead involves resurrecting a corpse (including chickens and such), not conjuring a skeleton out of hammerspace. (Atronachs are still hammerspace summoned.)
8. Killshots are varied depending on the weapon, the point of body aimed at, whether you have a shield, spell, or weapon held in your other hand, and whether your target's front or back is facing you.
9. Falling dragons eliminate bushes and such, scattering debris and leaving a scar of bare ground behind.
10. Damage on dragons *appears* to be locational, shooting one in the head with a bow appears to deal more damage than shooting it in the hip.
11. Water has current now.
12. 150+ Dungeons
13. Signposts greatly improved and the number of towns is greatly increased, small towns now also rate signposts. (Riverwood alone has 7 signs leading away from it.)
14. Lightning attacks will deal double their physical damage in magicka damage.
15. There is at least one dwemer ruin in skyrim.
16. Falmer confirmed.
17. Much more of the wildlife is now set to ignore you rather than kill you on sight.
18. ~200 starsign perks.
19. Enemies no longer stare blankly when you sneak snipe their buddy who they were just talking to.
20. Level design appears much improved with far fewer encounters of enemies that are just standing around, waiting to kill you.