We're very pleased to announce that the ArcGIS Runtime SDK 10.1.1 for WPF is now available for download from the Customer Care Portal: http://customers.esri.com/.
Make sure you take a look at the Release Notes for a list of enhancements, changes and known limitations in this release:
http://resources.arcgis.com/en/help/runtime-wpf/concepts/index.html#/Release_notes_ArcGIS_Runtime_SD...
... And here are some other resources you may find useful:
Blog Announcement: http://blogs.esri.com/esri/arcgis/2013/01/17/arcgis-runtime-sdk-for-wpf-10-1-1-is-here/
Resource Center: http://resources.arcgis.com/en/communities/runtime-wpf/index.html
Conceptual Doc: http://resources.arcgis.com/en/help/runtime-wpf/concepts/index.html#//017000000031000000
*New* Samples: http://resources.arcgis.com/en/help/runtime-wpf/samples/index.html
API Reference Library: http://resources.arcgis.com/en/help/runtime-wpf/apiref/index.html
Sample App download (if you don't have the SDK): http://www.arcgis.com/home/item.html?id=ace12032e3db4314b7ba7ee5b341c80c
Cheers
Mike
The current WPF SDK is now the version 10.2.3. It can be downloaded from here.
If you start a new project you should also consider using the new .Net API.