I have a client app that connects with asmx web services to my datacenter, in fact I really have serveral that work that way...
so the contract between the service and the client just has classes that hold data.
inside the web service i use DLINQ to do stuff but anything that goes to the client or comes from the client has no traces of LINQ.
and I have CE handhelds and WIndows Desktops that share the same set of web services.
now as I am updating the cleint apps they are starting to use LINQ localy to work with the local Objects... but again when the data goes out it's plain old classes that hold data.