The ArcGIS API for Microsoft Silverlight/WPF and ESRI MapIt, two new products in the ESRI suite, were released during the 2009 Users Conference in early July. Now, each has it's own blog hosted by ESRI.
Silverlight/WPF Blog: http://blogs.esri.com/Dev/blogs/silverlightwpf/
ESRI MapIt Blog: http://blogs.esri.com/Dev/blogs/mapit/
Both are available their respective resource centers as well (Silverlight/WPF, MapIt).
I'm the lead product engineer for both products, so I've been busy working with a group of extremely talented developers at ESRI to build and get them out the door. The ESRI blogs should provide you with some great information about both products... good times ahead for sure.