Personally, I'm strictly a little bit rock n' roll, but kudos to Rock Band 2 for something different: the Going Country Pack. The songs are as follows:

"Sin Wagon" by the Dixie Chicks (pictured, no relation)
"Gunpowder & Lead" by Miranda Lambert
"Hillbilly Deluxe" by Brooks & Dunn
"Mud on the Tires" by Brad Paisley
"Free and Easy" by Dierks Bentley.

I've heard of the first group (they're the ones who hate President Bush, right?), but the rest of that is all Greek to me. A discreet 01 after pack's the name implies more will follow.