A portion of a CrispyGamer interview with Harmonix's Chris Foster...

Crispy Gamer: What was the actual involvement of the remaining Beatles and the Beatle widows in the game? Did they just lend their name, or...?

Foster: No. The shareholders, as we call them -- Paul and Ringo, Olivia and Yoko -- were really creative partners throughout the project. They were involved in picking and approving the song list, the venues we went into. With the dreamscapes, they saw storyboards of all of the material, and gave feedback on whether or not they felt like those interpretations supported the songs in the way they wanted.

They looked over all the characters, the animations ... they really kept us honest on whether we were capturing the spirit of the band as they were performing, which was a huge challenge for us. With Rock Band, you've got these avatars that are, you know, anyone, so it's pretty easy for you to believe in them. But when you know who the Beatles are, and you know the joy in their faces when they play, you have to capture that on-screen; you have to be true to that, and they were really good about keeping the standard high.

At every milestone they improved it. I think Sir Paul McCartney heckled our project lead's bass-playing when he saw one of the game demos. So yeah, they were involved. I'm not going to put words in their mouth, but seeing all four of them at the Microsoft press event is about as validating as everything. They don't get together for almost anything ... it has to be something important, something they believe in.