Hold onto your hats because this could be major news in the rhythm game world. Tomorrow at 10am EST, Apple Corps Ltd. (not iPhone Apple, but The Beatles catalogue Apple) and MTV will announce an "exclusive agreement to develop unprecedented global music project."
While we have no hard evidence that this has anything to do with Rock Band, it wouldn't surprise us that part of the deal would include bringing The Beatles to the game in some form. We'd guess something closer to the AC/DC Track Pack over regular DLC, but we just don't know at this point.
The agreement, whatever it is, is exclusive to MTV, which would basically rule out The Beatles for Guitar Hero if any of the catalogue is even coming to the video game world.
We'll know more tomorrow.
UPDATE: The Wall Street Journal is now reporting that MTV has licensed music from The Beatles' catalogue for use in Rock Band, but does not yet know concrete details like price, date, or the form the music will take. Warning, the story is based upon the reports of "several people familiar with the matter" and should still be considered conjecture.
Thanks to G4tv.com user Firestorm76 for the tip!