Gmail will be rolling out a beta service called Priority Inbox to all Gmail users over the next week. You can check out the new service once the red ‘New! Priority Inbox’ link shows up in the top-right corner of your Gmail.
Priority Inbox will work by adding three different sections to your Inbox: first for important messages, second for starred, and third for everything else.
The service will automatically elevate messages as they come in from the ‘Everything else’ to the ‘Important’ section based on criteria like how frequently you open those messages or how often you e-mail the sender. It will also learn as it goes, much like the spam filter.
You can see the concept a little more with their cutesy promo video:
You can read more about it with the Google Blog announcement or at gmail.com/priorityinbox.