Called Priority Inbox, the feature will be released with the beta, or test, label and is being described for now as "experimental" by the company.
All individual Gmail users will gain access to it in the coming days. Availability for people who use it as part of Google Apps will depend on whether domain administrators allow their users to activate "pre-release" features.
The motivation behind Priority Inbox is Google's conviction that the problem of email overload continues getting worse, forcing people to spend much time and effort managing their inbox both for personal and work-related matters.
Priority Inbox is an additional, optional view of inbox messages. People who choose it can toggle back to other more conventional views, such as listing messages chronologically by arrival timestamp or alphabetically by the senders' names or subject lines.
"Gmail's Priority Inbox is part of a broader trend to help users cope with email overload and promote inbox efficiency," said Gartner analyst Matt Cain via email. "There is a thriving market for Outlook plug-ins that help users winnow large volumes of mail."
Those include tools from Xobni and ClearContext, while Microsoft itself has added inbox-efficiency features in Outlook 2010, Cain said.
"The large consumer base of Gmail users, however, will give immediate and widespread exposure of this message triage approach, which will in turn spark demand for similar services in the enterprise," he added.
While many email programs let users set up filters and rules for their inboxes, the manual process can be complicated, so Google simplifies it by building the functionality into Gmail via automated algorithms, said Rebecca Wettemann, a Nucleus Research analyst. "Information overload continues to be a problem and this is a nice step to drive savings," she said via email.
"Unfortunately, we'll all still have to be on the lookout for emails that don't fit the patterns that can be important," Wettemann added.
With Priority Inbox activated, Gmail divides the inbox into three sections: the top one contains the most important and unread messages; the middle one has messages that have been flagged by users with a star to highlight them; and the last section has all other messages.
Matthew Glotzbach, director of product management in Google's Enterprise unit, sees Priority Inbox as a sort of inverted spam filter which, instead of blocking and setting aside unsolicited messages, prioritizes items in the inbox so that users can attend more quickly to the most important emails.