Spam isn't the only thing that clogs up your inbox. Because only a fraction of the emails we get are high priority, they're sometimes lost in the barrage of regular emails that we get. Google is trying to fix that with a new feature that sorts your important, high priority emails that need addressing straight away from the not so important correspondence that you can probably take a few days to get back to.
Dubbed the Priority Inbox, the beta feature acts sort of like a turbo spam filter, learning your Gmail habits by looking at what emails you read and who you frequently respond to. It then splits your inbox into three sections, showing the most important in the first, top section. Underneath that are your starred emails, and under that is an 'everything else' inbox with all your regular emails. You can also add more boxes to this (such as 'unread and important') and tweak a number of other Priority Inbox settings.
Obviously it doesn't get everything right, but it's reportedly pretty accurate. If it does mislabel something, all you have to do is mark it unimportant/important yourself (by clicking the little yellow label seen above) and all mail going forward will be affected by your interferance. The more you use it, the more accurate it will become.
You should see Priority Inbox hit your Gmail in the next week or so as Google is rolling it out to all users. Let us know what you think!