When you own both sides (client and service) it can be more effective for developers to share assemblies for shared types, instead of relying on proxy generation to duplicate types from WSDL. Furthermore, if you want to work with strongly typed collections at the client, and I don't mean BindingList<T>, you may want to specify which collection type.

Here's the SvcUtil command to make this a reality:

One of the reasons that I blogged this seamlingly obvious instruction is because I got caught using a single quote (List'1) instead of a backquote character (List`1) and things were not working quite right. I didn't see it (better glasses?) but Eugene on the WCF team helped me find my way. It's the little things that take up your time!

Cheers!