If Harmonix could have updated, they would have. What other reasons would they have to delay the content?
I haven't seen any new dlc for Rockband since 12/18 and the Elton John pack. I'm looking at the store right now, in fact, and I see there's no new content this week either.
Why would anyone want to use the psn store to look for DLC? What's wrong with the in game store menu?