OK, so I'm starting to get to grips a little more with the Repository pattern.  Still got a long way to go, but it makes sense and in true XP style I'm going to run with it.

The namespace/deployment overview is as follows:

I've hidden some of the extra features, such as the DTO namespace.  The BusinessObjects encapsulate the 'raw' DTOs, which are used primarily in serializing the data as JSON via the WebService.

I've also not shown that the RepositoryFactory (and subsequent Repos) could be used directly without having to go via our WebService.

Remember that you can't just go to a BusinessObject and ask it to fetch itself - ALL data access is managed via the Repository.

I've also kept the interface deliberately simple - I don't want to be introducing LINQ goodness at that stage.  Everything is POCO.

You can find a related SO post here - http://stackoverflow.com/questions/741490/repository-pattern-pocos-or-iqueryable/741558#741558