A while back I remember reading Ian Griffiths post on Expression Trees and thinking, huh? 
After reading it I knew that what he was talking about was cool, I just didn’t understand it. Months later I came back to his post and can really appreciate what he’s talking about. Since the original read of his post I’ve dug into LINQ a bit more and come to understand some of the new C# 3.0 features.
Expression trees are how DLINQ will come to support more then just SQL Server. They’re also what makes DLINQ able to intelligently build targeted SQL for a given LINQ “query” (as discussed in my Getting started with LINQ post). I’ll be very interested to see how else expression trees end up being used when C# 3.0 becomes more mainstream. How much longer do we have to wait? 