Building Mashups?

Mashups are applications that take data from different sources and combine it to form new services or user experiences. By providing open, accessible APIs, the Windows Live Platform offers the opportunity to create mashups using the core services and data of Windows Live. Now you can build applications and mashups that combine your innovation with the power of Windows Live services and social relationships. To create highly interactive mashup web sites, have a look at the ASP.NET Atlas Framework: Atlas Showcase. This showcase highlights applications built on Atlas, a free framework for building a new generation of richer, more interactive Web applications. Atlas makes it easy to take advantage of AJAX techniques on the Web.

Good starting point to explore the APIs is the Windows Live Dev Portal and of course MSDN Online have a look at the Windows Live Developer Center on MSDN.