I've built a framework to use RIA Services in silverlight applications without using the DomainDataSource. I found myself implementing a Filter class like FilterDescriptor and I was implementing a way to dynamically generate Expression objects to include
in my EntityQueries.
When searching for a common approach in RIA Services I found that you are doing this in an internal class named LinqHelper. I think it would be very nice if you made this class public instead of internal. I believe it would make sense to expose this functionality
to be used outside of DomainDataSource.