Full House Poker, described as a way to "bet your way to fame as you compete against your friends and thousands of other players around the world in live Texas Heat poker game shows." The concept sounds extremely like 1 vs. 100 with a coating of poker paint, allowing players to pick up XP and other rewards (including "unique tells and avatar accessories") by playing poker in "regularly scheduled episodes."
Sounds fun! The email also stresses that the beta is "highly confidential" (whoops), and that it requires an Xbox Live Gold subscription in the US, Canada, or Mexico. Note that those restrictions are only on the beta, and might not be on the full game. But the email says the game will be rated T for teen, thanks to "simulated gambling." 1 vs. 100 is unfortunately gone forever, but it looks like Full House Poker might be Microsoft's second foray into episode-based massively multiplayer gaming.