Martin Bennedik developed a WPF Integration Adapter for the Validation Application Block to go along with the ASP.NET and Winform Integration Adapters that ship with the VAB.
Per Martin-
"The Validation.Integration.WPF project contains the two classes EnterpriseValidationRule and ErrorProvider that you can use in your own projects (under BSD license).
The WPFValidation project can be compiled together with the validation quickstart from the Enterprise Library 3.0. It is the same quickstart sample rewritten for the WPF integration."
Learn more.