Guitar Hero has become the first video game to reach 1 million fans on Facebook, trailing only Mafia Wars and Texas Hold’Em Poker on the overall PageData leaderboard for all games. This is not the quite the same achievement as selling a million copies of the game — and, in fact, Guitar Hero has sold 7 million times in 2009, and 38 million total around the world, so it’s already doing pretty good.

All that said, the popular music game, now in its 5th version, has been steadily gaining fans not just because it is a popular game, but because it has an active Facebook page. It features plenty of interaction between fans on the wall, numerous events and good coverage of those events, and a comprehensive collection of videos and photos both from the Guitar Hero staff and the game’s fans.

Rock Band, a similar game to Guitar Hero, made by rival gaming giant Electronic Arts, currently trails its counterpart by a significant margin, with just over 313,000 fans. Rock Band has made some recent efforts to gain more of a foothold on Facebook, most notably with its Advance Into Overdrive Challenge, but the actual fan page still lacks the level of content and interaction found on the Guitar Hero page.

Guitar Hero is also making the most of the Facebook page by cross promoting its presence in other social networks, with a Twitter tab showing its most recent Tweets, and a fairly lengthy list of links to other promotions, sites and endeavors that feature the game. The game had a popular iPhone application for a while, but the recent addition of a similar app from Rock Band for the iPhone may steal a little of that thunder.