Yesterday, Valve announced that Source will be available as middleware on the 360. Joystiq went back and asked them a few questions about what exactly that means to gamers. From the article: "The version included with our games (A.K.A. the MOD tools) includes a ton of tools and code for the creation of new products. However, there is a fair amount of code reserved for the 'Pro' version. It is certainly possible for end users or professional game designers (who are moonlighting) to create something with the tools included with purchase of our games, and then defer any decisions about licensing and sales until they've got something working. This was exactly the case with Counter-Strike, Day of Defeat, The Ship, and others."