The article has been taken down but
Joystiq and
Kotaku has articles on Computer and Video Games detailing that the December 2nd will be the day you get a dashboard update that will allow for downloading of old Xbox 1 games via a scan from the official Xbox magazine. Initially the games available will be
Fable,
Indigo Prophecy,
Crimson Skies: High Road To Revenge,
Crash Bandicoot: The Wrath Of Cortex,
Burnout 3, and
Halo: Combat Evolved. Pricing is said to be $15 which to me is a tad bit expensive since you can grab these games for cheaper at used game stores. Perhaps this is why Microsoft has been a little slow in backwards compatibility lately. It's good that they are getting into the digital distribution of previous generation titles on the 360. They are the last of the big three to do this so better late than never.