Tank could be for Wargaming.net
. They have a banner for the recently-announced World Of Warships
somewhere in the building - tank could relate to their World Of Tanks game, but that's 2 years old now. Still officially "in beta" though, so could be those guys. They had a couple of tanks parked outside the Eurogamer Expo in 2011.
Or could be Gaijin's Warthunder
. Also beta, it's currently just aerial combat (in competition with Wargaming's World Of Warplanes) but they're supposedly bringing in tanks and ships too. Might be announced at E3.
Could be for anything to be honest. It's an American WW2-era Sherman, I can tell that much.