Speaking to Kotaku at CES, Xbox 360 group marketing manager Albert Penello said Microsoft has "kind of hit the point of diminishing returns" with freely-offered backwards compatibility. "I don't know if we have plans to do any more releases," he conceded.
Microsoft has often stated its goal with backwards compatibility was to cover all of the most successful Xbox titles, and Penello believes the company has achieved that. A full list of titles, last updated in November 2007, is available on Xbox.com.
Meanwhile, the next title to hit Xbox Originals is Criterion's Burnout 3, according to the basically-official Gamerscore Blog. It will be available Monday, January 14 for 1200 Microsoft Points ($15).