At the ‘Start’ screen in The Beatles: Rock Band for the Xbox 360, enter the following code using the guitar/drum controller in order to unlock special bonus photos and Beatles art:

Blue, Yellow, Red, Red, Red, Blue, Blue, Blue, Yellow, Red

The same cheat also exists for the Nintendo Wii and PS3, for these platforms however the cheat code is as follows:

Blue, Yellow, Orange, Orange, Orange, Blue, Blue, Blue, Yellow, Orange