I'm sure I'm not the only one who is even a little excited about this game!
The trailer is on Play's page for the game!
There are 40 tracks including the Jackson 5 ABC!
Rock Band: Unplugged creates a full band experience in the palm of your hand by combining traditional beat match gameplay with key elements from both Rock Band and Rock Band 2, such as overdrive and chords. Your hands are the "peripherals" in Rock Band: Unplugged, allowing you to take direct control of the lead/bass guitars, drums and vocals. In addition, players can expect a rich Rock Band experience with fully functional modes like World Tour, Band Survival and Warm Up and a robust character creator for full customisation.
Rock Band: Unplugged will feature over 40 master-recordings including nine exclusive new songs that will debut on the PSP system. Plus, Rock Band: Unplugged will include the first fully-featured in-game store for downloadable content on the PSP system in Europe, leveraging the PSP system's wireless capabilities.