A new Live Search SDK version 1.1b, 3/15/08 with samples for Visual Studio 2005 is up and ready for download. According to the download page:
The Live Search SDK provides documentation that describes the core concepts, requirements, development guidelines, and class library for the Live Search Web Service. The SDK also contains sample code that demonstrates application development techniques using the Live Search Web Service.
More information can be found at the Live Search Web Service Development Forum, including "additional applications, including those written by members of the community and in a variety of Open Source languages".
Windows Live, Live Search, SDK