To get your website tracking this you must add a new server side code snippet to your mobile website. It's not clear yet however if you can also track traffic from mobile apps to your website, an issue addressed by Danny Sullivan several months ago. That will be figured out soon no doubt.
Another big chance is the "Analytics Intelligence". Google launched an algorithmic driven Intelligence engine in which you get automated alerts of significant data patterns in your site metrics. This feature could really save time for those working on large sites.
The other changes made include more more analysis features, more power and more flexibility to help get more out of analytics. And to be honest: there are very useful new features amongst them. A quick overview.
Engagement Goals: with this feature it will become easier to measure user engagement and branding success on your site.
Advanced Analysis Features: Google added the Advanced Table Filtering feature. This allows you to filter the rows in a table based on different metric conditions.
Unique Visitor Metric: You can now select Unique Visitors as a metric against any dimensions in Google Analytics.
Multiple Custom Variables: You can customize Google Analytics and collect the unique site usage data most important to your business.
Sharing Segments and Custom Report Templates: you can share custom reports through a link which you can send anyone who has an Analytics account.
Custom Alerts: Next to the intelligence-alerts you can now also set up your own alerts, allowing you to get triggers on dimensions an metrics via e-mail or in the user interface.
Google also added a couple of videos explaining a couple of the features: