Google has updated their free Gmail service with what's in effect the reverse of their spam filter. Gmail Priority Inbox is an optional service that, using the same technology that powers the spam catcher, predicts which messages will be of most interest to the user and pushes them up to the top of the list. There they sit on top of any starred messages, with the remainder of the inbox underneath.
Video demo after the cut
According to Google, the system works from a user's attention history: the messages they read, and those they reply to. Incorrectly prioritized mail can be downgraded, teaching the system in the process, while missed important messages can be flagged in a similar way. Gmail Priority Inbox will be rolled out over the next few days, to regular and Google Apps users; we'd particularly love an Android version, which would be useful for quickly triaging new messages while snatching a few seconds on a mobile device.