In an exclusive interview with RollingStone.com, guitarist Kirk Hammett confirmed that Metallica will be heading back into the studio this coming May. But apparently the group isn’t working on a new album. Hammett told RollingStone.com the following:

“We want to record it in two weeks.We had planned on doing it in March, but we pushed it back to May. I don’t want to give too much away, but it’s not really 100 percent a Metallica record. It’s a recording project, let’s put it that way. Without getting too deep into it, it’s more a recording project than a bona fide Metallica album. Whether or not we can pull it off in just two weeks remains to be seen.”

This comes shortly after drummer Lars Ulrich revealed in a separate interview that Metallica were indeed planning to head into the studio this Spring. Your guess as to what “secret project” Metallica is working on is as good as ours (though don’t hold your breath for Guitar Hero: Metallica II). Whatever it is, though, it’ll be cool to possibly have new Metallica music out by the end of 2011. We’ll keep you updated when more is revealed.