Unannounced by Harmonix the 1.4 patch for Rockband on PS3 was released today. Now songs are available for purchase in-game before they are released on the standard PS store. The in-game music store is fully working again (it was broken after the new PS store launched), but the in-game store is still using the old store interface.
Here's a link to the N4G.com Blog regarding the 1.4 patch
http://n4g.com/up/30969/BlogPost-136179.aspx