The Gamerscore Blog has some information about the upcoming release of Fable 2. Three minigames will be available in the Pub: Keystone, Spinnerbox, and Fortune's Tower. As you can tell from the screenshot above, these minigames are based on casino games. These minigames will be released as DLC for 800 MS points ($10). However, you can get the games for free by preordering Fable 2 from participating retailers. It's unknown what co-op features will be available in these minigames, if any, but getting content for free is always newsworthy. More in-game content and other goodies will be available in the collector's edition of the game, but the Pub games are available with even a regular edition preorder.
All money earned in these games are then transfered to Fable 2 on release. It's also assumed that the actual mini games will be in Fable 2, but this is sort of a wet your appetite kind of thing.