Ratcheting Up The Excitement Level For Ratchet!

I'm always excited by the prospect of a new Ratchet & Clank game. Although, to be honest, the latest trailer, while highly entertaining and humourous, doesn't really answer the burning question that I've had about the upcoming addition to the R & C franchise, which is: why is it called A Crack in Time? Is there actual time travel involved, or just some sort of "threat to time" introduced?

(Oh, and this trailer for Aliens Vs Predator: Colonial Marines looks pretty awesome, too!)