Google on Tuesday plans to introduce a Priority Inbox for Gmail that it says could save an average of 46 minutes of e-mail processing time per week per user.

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For employers, that could translate into a productivity savings of over 40 hours per year. In monetary terms, that would be worth over $1,100 annually per Gmail user for private sector companies and almost $1,600 annually per Gmail user for government agencies, based on average employee compensation costs reported by the Bureau of Labor Statistics in June.

Priority Inbox is Google's attempt to deal with information overload. It's a visually distinct area of one's Gmail inbox that displays messages deemed to be more important than the rest. The assumption is that Gmail users can work more efficiently by dealing with important e-mail and deferring or ignoring less important e-mail.

Priority Inbox relies on a filtering system to sort significant messages from less significant ones. It differs from Gmail's existing user-configurable, keyword-based filters in that it filters automatically, can be corrected when it fails, and tries to learn on its own.

Google suggests that Priority Inbox is like the Gmail spam folder, except for the good stuff. Training is simple: A "+" icon puts e-mail into the Priority Inbox; a "-" icon takes e-mail out. The system also considers frequently e-mailed people to be important.