The download that installs the Visual Studio Tools for the Office system 3.0 Runtime, which is required to run VSTO solutions for the 2007 Microsoft Office system built using Microsoft Visual Studio 2008 has been released.
http://www.microsoft.com/downloads/details.aspx?FamilyID=54EB3A5A-0E52-40F9-A2D1-EECD7A092DCB&displaylang=en