Gamespot has posted the recording of Chris Butcher's talk at GDC this year titled "Destiny: Six Years in the Making." You can watch it over on their site or on their Youtube channel, and here is Bungie's own description of the talk:
At Bungie, we built games based on the Halo engine for ten years. However, by 2008 it was beginning to show its age and there were many core systems that were ill-suited to a modern game development environment. For our new game, Destiny, we sought to develop an engine that would last us just as long as the Halo engine had. This talk will cover the six-year development arc of the Destiny engine, from inception to ship.
(Thanks to uberfoop for posting about it on the forum, even if I didn't notice until after the fact!)