(Update: This image is no longer available. Currently there are no plans to create another SharePoint 2010 demo image. Visit http://dev.office.com for information on building SharePoint apps)
The RTM version of the SharePoint 2010 and Office 2010 VHD files are now available for download. This includes Windows Server 2008 R2, SharePoint 2010, Office 2010, Visual Studio 2010, SQL Server 2008 R2, Exchange 2010 and more. See the download site for a complete list of software. This is the the same virtual machine that we do all of our demos and presentations with.
Download SharePoint 2010 VHD: (Updated with SP1 - 9/15/2011)
SharePoint 2010 Developer Training Kit
If you are new to SharePoint 2010, download the SharePoint 2010 Developer Training Kit.
This training kit has videos, hands on Labs and Demos that work with this VHD.