Holy Sh*t! THQ has announced that they're going to be collaborating with South Park Digital Studios and Obsidian Entertainment to create South Park: The Game. For reference, Obsidian are the masterminds behind famous RPGs like Star Wars: Knights of the Old Republic 2: The Sith Lords and Fallout: New Vegas.
According to the press release, South Park: The Game is to be, "an epic role-playing adventure that will allow the user to befriend Stan, Kyle, Cartman and Kenny and explore the quiet little mountain town like never before." It's scheduled to release for the Xbox 360, PlayStation 3, and PC in late 2012.
Many years ago, I actually won a copy of South Park for the Nintendo 64. It had its moments, the cow rocket launcher was pretty amusing at first, but the novelty wore off after a while. Obviously they'd be working with better tech these days but I'm guessing the result may be the same.