100% this is from Crackdown:
I left rumor in the title because I don't have a link to the post show talk.
spencer confirmed it after the post show to a fan asking a question about it.
Pretty interesting if true. Crackdown is known for having over the top explosions, combining that with Red Faction-esque destruction like we saw in the CG trailer would be insane in a sandbox.
Edit: fake mod abuse
Not a rumor. Confirmed by Phil:
I called it? I called it.
Yeah, here's a video they released after the build conference that shows the demos side by side with same destruction sequence (the cloud one finishes first so they go on to do a lot more destruction): http://youtube.com/watch?v=ECsbaO1XGBU
Better video since it isn't "shady," as some put it. They actually released it because people didn't like that he turned his back to the building in the live demo. This tech seems pretty cool, looking forward to seeing what they do with it in crackdown.