A while back I did this post talking about how WCF contract definitions should model the messages being passed and not use business  objects. This inevitably  means that you have to translate from the Data Transfer Object (DTO) in the contract to business object and back again. This can feel like a lot of overhead but it really does protect you from a lot of heartache further down the line.

However Dom just pointed out the AutoMapper to me. This is in its early stages but looks like the kind of library that will really take away a lot of the grunt work associated with using DTOs – kudos!