You don't really need the PDK to interoperate with .NET with Perl unless you want to explicitly want to use classes from a managed assembly directly in your Perl code without using COM (via Win32::OLE) or SOAP.

The slides of the talk I gave on this very subject at yapc::Europe last I can't seem to find at the moment or I would point you toward them. Basically the bottom line is that you should be conservative with the data structures you are a going to share between Perl and .NET and that you will get better results with SOAP between the two if you don't think of it as an RPC mechanism rather as a document-centred message passing. C# Web Services clients also much prefer a WSDL document and currently the only reliable way to get one of these for a Perl server is to make it by hand.

/J\