Speaking to a packed house during the QuakeCon 2010 keynote address and the follow-up Q&A session, John Carmack said that he sees a real future with cloud-based gaming.
He also talked about 3D TV technology (he doesn't know if the value or usefulness is there for consumers) the current crop of motion controllers (he says "they're not of value to id") and dedicated servers (he has not decided how or if RAGE will support dedicated servers), but the most interesting comment has to do with cloud based gaming services, which he calls "interesting" - even though he hasn't tested any games that use it.
Here's an excerpt from a Shacknews article on Carmack's comments:
On Cloud gaming services: "Cloud gaming is interesting. I haven't tested the products out there now, but it's not exactly clear when the market will sustain it. There's no question that eventually that will be the model a lot of people will play games with." Carmack is also optimistic that cloud gaming will solve alleviate problems like draconian DRM and cross-platform development. Linux, for example, might benefit greatly from cloud gaming since native Linux ports of a game would no longer be required.
While Carmack isn't Nostradamus when it comes to predicting what technologies and ideas will be big, he's usually keen to support those he thinks are worthwhile.