A moderator of the RockBand.com message boards (hmxsean) had recently posted the following:
Due to circumstances beyond my control we won't be announcing next week's DLC until Monday afternoon. Probably around 2... maybe earlier, maybe later... but I am aiming for 2. That's eastern time, post meridiem [sic].
See you then,
PS Go, go gadget conspiracy theories!
The DLC pack is right now expected to arrive on its usual scheduled dates (Tuesday for XBox Live, Thursday for the PSN Store).