The announcement will be made today at the SharePoint Conference 2009 in Las Vegas, where Microsoft chief executive Steve Ballmer will announce the public betas coming in November. An exact date has yet to be fixed, according to the firm.
Also to be announced are two new SKUs, or editions, of SharePoint 2010, due to be available when it launches sometime in the first half of 2010, along with Office 2010.
These new editions will target businesses interested in building public-facing web sites around SharePoint, according to Microsoft.
One will be an on-premise version aimed at small businesses, while the second will be a hosted option, whereby SharePoint and the site will reside inside a Microsoft datacentre.
"This is for customers that want their web site hosted by Microsoft. We are going to offer that option in 2010," said Steve Marsh, SharePoint product manager for Microsoft UK.
However, the new editions are little more than new ways to purchase SharePoint for new customers, according to Marsh.
"That's the beauty of SharePoint. The SKUs are all to do with different licensing, but it's all still the one product," he said.
SharePoint 2010 is set to be "the biggest SharePoint release ever," according to Marsh. "We've seen fantastic momentum behind SharePoint, which has turned out to be one of the fastest growing Microsoft products ever," he said.
At the conference, Microsoft will detail more investment the company is making in enhanced capabilities for web sites built on SharePoint.
The new editions are part of this, but Marsh declined to disclose any further details ahead of the conference itself.