80% of mobile page views relating to the Olympics were from apps

"During the Olympic Games, it was apps that consumers turned to for their sporting content, not the mobile web. That's according to information firm Nielsen, which tracked usage of LOCOG's two main iOS and Android apps, Join In and Results, among a panel of 1,400 nationally representative smartphone users during the Games.
80 per cent of all mobile pageviews relating to the Games can be attributed to apps, and that number jumps significantly in terms of time spent - apps accounted for 96 per cent of all time spent using a London 2012 mobile property."

Source:  Nielsen data, reported by Mobile Marketing, 20th August 2012

Note - I'm assuming this is US only, although it doesn't explicitly say so