Microsoft plans to release Game Room for Xbox Live and Games for Windows - Live on 24th March. It will be free, but game cabinets and game-plays will cost, as previously reported.
Game Room will be the culmination of the "Block Party" ("House Party" in some regions) promotion for Xbox Live Arcade, which begins Wednesday, 3rd March with the release of Toy Soldiers (1200 MSP - £10.20/€13.96), and continues every Wednesday thereafter.
Buy all three of those games and download the free Game Room and you'll be given 400 Microsoft Points (£3.40/€4.80) back. What's more, you'll get an entire month of Xbox Live Gold membership for free.
Rebates will take up to four weeks and be issued after the promotion ends, which appears to be 31st March. You may want to read the small print on the Major Nelson blog.
Microsoft will also unlock multiplayer features for those three Xbox Live Arcade games for Silver members during the last weekend in March.
We'll offer our thoughts on Game Room as soon as we can.