It's semi-official: New data confirms that London 2012 was the first Mobile Games | #MoPR

From Robert Andrews at paidContent:

We have already reported strong mobile figures from the BBC (a third of web visits, a tenth of video streams) and NBC (16 percent of web users, 45 percent of video requests).

But (newly released) stats show even higher mobile engagement - 60 percent of visits to the official London2012.com site and apps came from mobile devices.