The only WPF exam is 70-511 (.NET Framework 4, Windows Applications):
http://www.microsoft.com/learning/en-us/exam.aspx?ID=70-511
I believe that it has not yet been retired, so you can still take it.
This has not been updated to newer versions of the Framework. The new exams about desktop applications are all about Windows Store Apps; WPF seems to have been abandoned from the point of view of certification exams.