This one belongs to the developer community (if you’re not a developer but user then you better download this). Microsoft Office Team has just released Office 2010 Beta Developer Training Kit, for the purpose of  providing training material for developers to gear up building Office Add-ins and Office Business Applications (OBAs) using Visual Studio 2010 with Office 2010 and SharePoint 2010 as the core platform.

As written on MSDN blog about this…

This training kit is an offline complement to the Office Learning Center and provides you with links to the videos but you’ll have the hands-on labs (HOLs), source code and presentations conveniently available on your machine. This is the same content that we developed for our ISV early adoption program called Metro, that we are now making broadly available to Office developers everywhere!

Here is the download link for Office 2010 Beta developer Training Kit