From the back of the package:
Sieze your moment of glory in the battle of the ballroom with an all new all-star cast, new dances, and more music! The competition has never been as intense or more fun.
40 New songs! Including hit songs: Mony Mony, Push It, Lady Marmalade, She Bangs, Bootylicious, Black Horse and the Chery Tree and more!
Dancing with the Stars: We Dance! is a video game based on Dancing with the Stars. It is the sequel to the original Dancing with the Stars game. It is on Activision's "Wee 1st" label.
The game's subtitle, We Dance, was derived from the Namco-Bandai games; We Ski and We Cheer, also for the Wii.
It is currently known that the game will feature new stars including Mel B, Apolo Anton Ohno, Joey Fatone and Jennie Garth and new professional dancers including Derek Hough and his sister Julianne Hough.
The Wii version will improve on the original with refined Wii Remote and Nunchuk controls. Other additions include new special "flair" moves. The Nintendo DS version will feature changeable outfits and swappable partners.
* All new stars from past seasons
* 8 new professional dancers: Including two-time champion Julianne Hough and Derek Hough
* 40 New Songs
* Engaging Dance Mechanics: All new, special flair moves. Improved gameplay includes score multipliers.
Source: Wikipedia, "Dancing with the Stars: We Dance!", available under the CC-BY-SA License.