Half-Life 2 on Xbox. As well.

German Xbox magazine AreaXbox (website here) dropped us a line to say that Half-Life 2 is in development for the green slab. Just not exclusively, as some worried that it might be. AreaXbox apparently contacted Doug Lombardi at Valve and was told that "Yes, we're also working on an Xbox version, though not releasing any specific details on that until after E3." That doesn't necessarily rule out other console releases - we imagine that an Xbox magazine only inquired after the one version anyway - but the incredible visuals witnessed in the screenshots probably do.