Although Mobile Phone usage has already passed fixed phone usage, mobile devices are still way behind laptops and PCs. A new data from Monetate Q1 2013 Ecommerce Quarterly shows that only 21% of the website traffic is via tablets and smartphones.
But we can still be optimistic on the rise of "mobile", since only 20% of mobile device usage is for browsing and 82% of the mobile media time is used on mobile apps. So be prepared to switch your mobile marketing from mobile browsers to mobile apps..
For more on the subject: http://www.smartinsights.com/social-media-marketing/social-media-analytics/social-media-ecommerce/