A beta version of Visual Studio 2005 Tools for Office 2007 has just been released.You can download the beta from here. It was developed under the code name Cypress.

VSTO 2005 SE Beta offers managed-code add-in support for six Office 2007 applications -- Outlook, Excel, Word, PowerPoint, Visio and InfoPath. It runs on Visual Studio 2005 Team System, the professional version of Visual Studio 2005 and Visual Studio 2005 Tools for Office.

The general manager for Visual Studio Tools for Office (or VSTO for short), K.D. Hallman has written an article on the features here in the VSTO forum on MSDN. These features include support for UI elements such as the ribbon, custom task panes and Outlook's form regions, plus design-time support for InfoPath's form templates.

Applications built on Office 2003 using Visual Studio 2005 Tools for Office will also run with Office 2007.