Alienware has perhaps the most exciting Steam Machine coming to market, and now we know when it will arrive. According to a tweet from Dave Oshry, a video game marketing exec attending Valve's Steam Dev Days developer summit, the company just announced that Alienware's Steam Machine will launch in the September timeframe. That's quite a ways away.

While we don't know the exact specs of Alienware's box, it is quite small at just three inches tall and eight inches on a side, and it aims to compete with next-gen game consoles in both specs and price. We tried a system that Alienware said was representative of the final machine in terms of performance, and its Intel CPU and Nvidia discrete GPU seemed capable of handling current PC games at 1080p. Valve certainly believes in the machine "This machine is the one that we think is actually going to serve the most customers and make the most Steam users happy," Valve designer Greg Coomer told us late last year.

At Steam Dev Days, Valve is also handing out free Steam Machines and prototype Steam Controllers to all 2,000 attendees, to help spur development for the new Linux-based SteamOS platform. They're getting the highest-end Gigabyte Brix Pro, an extremely tiny box just 4.5 inches on a side, which comes with the surprisingly powerful Intel Iris Pro graphics inside.

Update: Intel says it donated 1,200 boxes to attendees, not 2,000 as originally reported.