This sample shows how to process and render a skinned character model by using the XNA Framework Content Pipeline.

http://create.msdn.com/en-US/education/catalog/sample/skinned_model (XNA3.1 & XNA4.0)

SkinnedModel (XNA3.0)
SkinningSample.zip

http://www.xnaexpert.com/English/tutorials.html
SkinnedModel Tutorial (XNA2.0)