We first heard about Obsidian Entertainment's South Park RPG last week when Game Informer revealed the focus of its January issue's cover story. The mag is already going out to subscribers, so it probably won't surprise you to hear that some key details about the game emerged over the weekend via a NeoGAF poster.
The South Park RPG is built on Obsidian's Dungeon Siege 3 engine, though it sticks with the TV series' 2D style of animation. Your player character, a new kid in town, can be customized using one of five different classes: wizard, paladin, adventurer, rogue and an unannounced one that Cartman apparently picks for you.
Typical RPG trappings are there, but with a distinctly South Park twist; soda, for example, works as a health potions while Tweak's coffee includes a "haste" effect. Combat is turn-based, but it features active elements like timed button-pressing; the NeoGAF poster (and possibly the article) compares it to Paper Mario.
The last bit I want to mention is the game's menu screen, which takes the form of a smartphone. You'll use a Facebook-like app to track "the number of friends you have and your current standing with the various kid factions." It's a reasonable guess that the whole "new kid in town trying to be accepted" plotline will involve winning over those various factions by completing their quests.
All of this ought to sound pretty darn exciting if you're a South Park fan who also likes RPGs. There's a lot more detail in the magazine; make sure you give it a read.