Microsoft has announced that the public beta of SharePoint 2010 and Office 2010 is now available for download.
The public beta for SharePoint 2010 is available here: http://www.microsoft.com/downloads/details.aspx?FamilyID=77c30c6c-47fc-416d-88e7-8122534b3f37&displaylang=en (please make note of the system requirements and perquisites within this article http://technet.microsoft.com/en-us/evalcenter/ee391660.aspx)
The public beta for Office 2010 is available here: http://technet.microsoft.com/en-us/evalcenter/ee390818.aspx