From a recent Borderlands forum post:

"Borderlands 2 will reward veterans of the first Borderlands with exclusive character customization elements -- here's a look at the character heads and skins that are unlocked when Borderlands 2 detects save data from the original Borderlands!"

Wow. So that ups the extra stuff you can get by a bit. If you pre-order the game not only do you get the premiere club goodies and if your pre-order from Gamestop you get even more. But if you have a save file from a previous game you get a few more extras now.

Waiting for them to announce the bonus for booting Borderlands 2 for the first time. I really like the Sledge bonus head.