Microsoft Software Licensing and Protection Services
Microsoft just released a line of tools based on technology that was acquired about 10 months ago when Microsoft bought the Israeli startup Secured Dimensions.
The Microsoft SLP Services includes .NET Code Protector which helps protect .NET code against disassembling and decompilation & Licensing Services (also Online) which allows software vendors and publishers to more flexibly and effectively monetize their software.
If you want to test drive these technologies check the following :
Software Licensing and Protection Services 2008 - Code Protector SDK
SLP Services: Tutorial and Demonstration application
Another new release is the Windows Live ID Client 1.0 SDK
The Windows Live™ ID Client 1.0 software development kit (SDK) provides a managed API for Windows Live sign-in from within desktop client applications. Included in the release is a sample application together with its source code so that you can build your own client applications.