The Onion's AV Club got a preview of the game and more info has been given to us.

Drum Trainer:
"Rock Band 2 takes this a step further with the addition of an actual drum training program. I watched Teasdale demo this, and it resembles the game's practice mode, but with a large library of basic beats and fills: "Simple 8th Note Hats," "Robot Rock," "P-P-P-Panama!", "Upbeat Hats 1," and so forth, all playable on three kits – electronic, vintage, and "trashy." There's also a freeplay mode, where you can play drums over mp3's that you've ripped to your console."

No more randomly generated characters in Single Player:
"First off, the career mode. Rock Band 2 cuts the solo world tour, and it makes the concept of a "band" more flexible. Any number of people, online or off, can join a band: you can play by yourself with three steady non-player characters of your own design."

More info:
"two of the team members dropped hints about a different initiative: a path to bring more indie bands onto the Rock Band platform
- ...a "party-safe" mode keeps newcomers from accidentally hitting the wrong button and backing everybody out when you're trying to start the song
- Your characters don't have to stick to one instrument, giving you the flexibility to jump from guitar to drums
- You'll also be able to play whole albums automatically in the right order
- A risk and reward system will complicate the business end (of BWT)
"In the band world tour, you'll still compete for cash and fans, but you'll have more variables to play with. You can hire staff – promoters, your mom – to support your band or find new gigs. A risk and reward system will complicate the business end: hire a sleezy accountant and you may clear more money from a successful gig, or you may get robbed if you underperform. I couldn't tell how engaging this will be, and for detail, it can't compete with Shady O'Grady's Rising Star – but it gives spreadsheet wonks a few more tools to play with."
- ...the list of stars, including some serious legends, and one get that really surprised me
- ...you can buy the improved kit with a metal-reinforced pedal, quieter, velocity-sensitive pads, and wireless support on all platforms

Metal Pedal. yes! This game just sound better and better.
Also, the video list is in fact, fake.
Source