Just like Europe, SingStar will be getting an expansion disc here in the States. The disc offers the same SingStar experience as the original, but offers a different track list featuring 30 new songs. For newcomers to the series, this is a different way of getting the full PS3 SingStar experience. However, series regulars will have to swap discs if they want to have all the songs from Volume 1 and Volume 2: there's no way of ripping content from one disc to another, a la Rock Band.
SingStar is meant to be a constantly evolving platform, and we're assuming any new features added to America's Volume 2 disc will be applied via patch across all other SingStar games. For example, the US version of SingStar received a patch that contained all the new features added to the European Volume 2 game. One of the most exciting features for the upcoming expansion is the addition of Trophies -- exactly how that will work in conjunction with the SingStore is anyone's guess.