I ran into a versioning problem when I tried to use the latest version of FluentNHibernate with the latest version of LINQ to NHibernate because LINQ to NHibernate is built using a later version of the NHibernate binaries.
After doing a little search, I found a version of NHibernate which both LINQ to NHibernate and FluentNHibernate had been built against here.
So now, I can enjoy the same fluent interface to configure NHibernate and the use of LINQ query like this:
var onePiece = from s in session.Linq<Series>() where s.Name == "One Piece" select s;