While Amazon still shows the release as December 31, 2012 (meaning they have no idea what date to confirm), it looks as if an open beta is in the works.
If you are one of the 100 or so Vita owners that actually care about the game, make sure you sign up for the beta. There is a very short survey, and since your PSN info, qualification into the beta may be based on your actual gaming practices (trophies, purchases, etc).
I could usually give a crap about betas; most of the ones I receive via PS+ are nothing more than glorified demos. The LittleBigPlanet Vita one is different. Would really like to see how the game in the pre-release stages and offer some feedback.