Oblivion's leveling system
Which has already been confirmed as deleted.
Guns.
Agro animals that attack 100% of the time. Real wolves, bears, and lions eventually retreat if they're too hurt to continue fighting. They don't always attack (on Earth) humans, especially if they're not hungry.
guards/NPCs that can swim, even as they're wearing a full armor suit + heavy metal weapons
Oblivion's near-endless item carrying system
the ability to run faster than a horse (without magical means)
Orcs and lizardfolk speaking plain English 100% of the time, although I fear I'm gonna have to live with this in Skyrim. I'd like some other languages (or something that at least sounds like another language) from the beasties, maybe some of the elves as well.
Snow that doesn't stick or accumulate somehow (sounds like this is not going to be an issue, though.)
orcs and lizardfolk running bookstores and wearing finely-tailored clothing.
a lack of peaceful wildlife. We need more than deer, invisible birds, and a few sheep if the wilderness is to be more properly fleshed.
Bandits that have ebony, daedric and glass armour (cut & pasted this one from god-of-madness up above)
Can't think of anything else, but that seems enough. :whistling: