As you can imagine, we're working hard on the early stages of our Orcas release of Visual Studio. VSTO is the one SKU of Visual Studio that is closely aligned with Office. So, as we make our CTP (Community Technology Preview) releases between now and Orcas RTM, we'll aim to align them with Office releases.

Bill Gates announced the first VSTO CTP release at the Office Developer Conference this week. This build of VS is based on the Whidbey (VS 2005) release, and built against Office 2007 beta1 Tech Refresh. In order to get this CTP, you need to have the Office 2007 beta1 TR. Only customers currently registered with the Office 2007 beta 1 program (including the Office DevCon attendees) are able to install this CTP. If you're not on this program, you'll have to wait for a later CTP release which will be available to the general public.

The download itself, including an extensive readme is here.
A covering tutorial is here.

The primary goal of this CTP is to give Office 2007 beta 1 TR developers an early glimpse at some of the key new features and feature directions in the area of Office programmability. The next version of VSTO is designed to help developers take better advantage of those new capabilities in Office 2007, as well as to provide additional infrastructure to ensure .NET solutions in Office run more reliably, efficiently and securely. Feature highlights of _this_ CTP release:

• We've extensively strengthened the underlying VSTO runtime.
• We've changed over to use the new Office Open XML file format - no more hidden runtime storage control.
• We have add-in projects (both design-time and runtime support) for app-level add-ins for all the Office apps that support COM add-ins (10 of them).
• Runtime support for the new Office 2007 UI extensibility features (app-level custom task panes, customizable ribbons, Outlook custom form regions).
• Minimal design-time support for customizable ribbons only (design-time support always lags behind runtime support, and we'll be focusing on design-time in later CTP releases).

Note: As with any pre-release software, you should not install the VSTO 'v3' CTP on a production machine. Uninstalling this CTP might not bring your computer back to its original state. Hence, it is strongly recommended that you either set up a separate computer for this purpose, or create a backup image of your computer, before installing any of the software referenced here. Alternatively, use a Virtual PC.

Eventually, the next version of VSTO will be an independent product, much like the previous versions. Currently however, this CTP is available only as an update to Visual Studio 2005. Therefore, in order to install this CTP, you will also need a spare licensed copy of either VSTO 2005 or VSTS 2005. If you do not have one, then you may download and install VSTS 180-Day Trial at no cost from here. You will also need to install Microsoft WinFX Runtime Components - February CTP, which you can get here.