According to this article in the Denver Post, when South Park returns for their 10th season this Wednesday, the episode will include a riff on World of Warcraft. The article is not clear about whether WoW will be the sole focus of the episode or just a minor plot point.
South Park has a pretty good track record of video game parody, with the PSP episode and the original Towlie episode standing out. Cartman was especially proud of his 360 last season, but the poor guy had to settle for the Core model.
So what are we in for? Cartman griefing newbs on a PvP server? Butters meeting a hot Night Elf? You can catch the episode this Wednesday night at 10 PM on Comedy Central.