The Kinect Sports Party Pack is available today and is free to download from the Xbox Live Marketplace. The Rare title released at Kinect's retail launch.
TheAchievements are for Pinvaders (Bowling), King of the Ring (Boxing), Target Smash (Table Tennis), Rapid Runner (Track and Field), Super Striker (Soccer) and Fruit Splatter (Volleyball). There's no official announcement on this DLC yet.
Check outof Kinect Sports and see if it aches well, or just aches.