A lot of mods have been out for a while already on PC. I think I'm running around 25 right now. The Creation Kit is going to increase the amount of people who can make mods and it's going to let people work with functions they can't access at the moment. I'm looking forward to the same volume and variety we had with Skyrim and New Vegas/FO3.
I'm got to say, mods improve the game by a ton. Like Armorsmith Extended, for example, which lets you add Ballistic Weave to anything and lets you wear any clothing under your armor, or Spring Cleaning, which lets you scrap all kinds of buildings and junk you couldn't touch before. Snappable Junk Fences nearly made me weep with joy.
Oh, and Armorsmith lets you build a rocket pack you can use WITHOUT power armor. It's awesome, since I dislike power armor.
Console people have a lot to look forward to.