You don’t need to guess the answer to this question – the Metallica guys and Lou are releasing an album of their collaboration. From the Metallica site:
A few months ago our own Kirk Hammett hinted at a new Metallica project that’s “not really 100 percent a Metallica record.” While Kirk may have jumped the gun a little (and has since been properly punished with a series of push-ups!), we are more than proud to announce that we have just completed recording a full length album that is a collaboration with none other than the legendary Lou Reed.
Ever since we had the pleasure of performing with Lou at the 25th Anniversary of the Rock and Roll Hall of Fame at Madison Square Garden in October of 2009, we have been kicking around the idea of making a record together. Some of you astute Bay Area residents may have picked up news of recent Lou Reed sightings in the greater San Francisco area and we have indeed been working at our home studio at HQ on and off over the last few months.