VMware is reportedly branching off into the groupware business.

According to All Things Digital, the Dow Jones blog that majors in Yahoo’s doings, VMware is gonna take Zimbra, which has been on the block for at least a few months now, off of Yahoo’s hands, having been persuaded that it should move up the software stack and not be so focused on virtualization.

Yahoo bought Zimbra in September of 2007 for $350 million, apparently to compete with Google, but now wants to focus on its core business, whatever that may turn out to be. It’s expected to take a loss on the property.

The move, if true – and the blog claims “several sources close to the situation” – would put VMware in the open source e-mail and calendaring business.

Zimbra describes its Collaboration Suite as a “next-generation Microsoft Exchange server.”

Its AJAX-based widgetry also provides online document storage and editing, instant messaging and syncs to mobile and desktop client applications; the server is deployed on commodity Linux and Mac servers.

There’s a commercially supported version with closed source components such as a proprietary connector to Outlook for calendar synchronization.