Actually, I believe Stargate SG-1 did an episode where Ben Browder's character (sorry, I forget his name since I wasn't a frequent viewer) imagines he is fighting off zombies solo.
I think it was an episode where television producers wanted to make a series on the exploits of the Stargate team. (There is a crack by someone, to the effect, that zombies are overdone).
So, zombies have been the 'in' thing for awhile.
Not too mention, 'Shaun of the Dead,'...as well as the inferior remake to 'Dawn of the Dead' came out a few years ago. We also had 'Zombieland' and George Romero's 'Land of Dead'...'Diary of the Dead' (which wasn't as bloody as I thought it would be)....and 'Survival of the Dead.'
Now that I think of it, we had a somewhat released remake (with Mena Suvari and Ving Rhames) of 'Day of the Dead.'
AMC has 'The Walking Dead' coming soon...
There is also some movie that just came out, I forget the name, with hot Milla Jovovich...which has zombies...(Not very good, I hear; it's in 3D; Ali Larter looks hot in it...as well as some British chick...and some other chick playing some character named K-MART).
So, yeah, zombies have been 'in' for awhile...