VSTO...VISTA...VSTA.. It is sometimes becoming confusing for the students :). VSTA stands for the Visual Studio Tools for Applications and is a version of Visual Studio.NET 2005 that ISVs can license and embed within their own products to allow their users to extend these products. If you install Microsoft InfoPath 2007, you actually have the option to install VSTA along the ride and have the Microsoft Script Editor replaced by it so that you can extend InfoPath templates with .NET code directly instead of using VSTO. I have wondered a couple of times what I should tell about when to use VSTO and when to use VSTA for extending InfoPath. The results look the same, don't they?

Anyway, there is an on-demand webcast on the US Partner Readiness site titled ISV Touchdown Web Seminar: Overview of Visual Studio Tools for Application (VSTA) that is getting you started. It also explains the roadmap for VSTA.