Guitar Hero Metallica still doesn't have a firm release date in the US (though rumours suggest March). Doesn't have one in Europe, either, but it does have a firm release month.
And that month is May, Activision confirmed to Eurogamer yesterday. A two-month wait for PAL users seems a bit much, but then, with Kyuss, Slayer, Alice in Chains & The Sword along for the ride, we can endure the delay. Stiff upper lip and all that.
Guitar Hero: Metallica confirmed for May [Eurogamer]