Edd Dumbill has been looking into parsing RDF in C# (under Mono no less):
So I went looking for a C# toolkit for parsing RDF, and immediately encountered Drive, a 100% C# RDF parser. Drive was developed on Windows .NET but compiled painlessly under Mono. With a small amount of flicking through the API documentation and a test program or two, I was ready to go within the hour.
Very cool stuff indeed.