Microsoft has sort of detailed its Games with Gold initiative.
Two games a month will be available for free to Xbox Live Gold members with a new title being added on the 1st and 16th of every month. This will continue until the end of the year.
Xbox.com goes on to say that: “Each specially selected, fan-favorite game will be available to download only for a limited time, so grab them before they’re gone and keep them no matter what.”
Currently Fable III is available to all Gold Members until 30 June, at which point either Halo 3 or Assassin’s Creed 2 will become available.