No longer will visitors to your site receive four first party cookies from GA, but one. This one cookie will contain a unique visitor ID that will enable your website to read and store it when someone logs in, for example. This new “measurement protocol” then allows you connect your information about the anonymous visitor ID in Google Analytics. If that visitor’s ID then logs in again on your site, but this time from an IPhone, Google Analytics understands that it’s the same visitor using your site, but on multiple devices. Goodbye visit-centric analytics, hello visitor centric analytics.
Because of the data import implications – this will probably be a Google Analytics Premium feature, but that’s my view – it’s not official. Get listed for the beta. And find out more here. Also check out Google’s official post on “Universal Analytics”.