Just to make sure everyone sees it, I have start to work on a Linq implementation for NHibernate, you can see what already works here:
http://ayende.com/Blog/archive/2007/03/16/9117.aspx#14050
Details about the implementation can be found here:
http://www.ayende.com/Blog/archive/2007/03/17/Implementing-Linq-for-NHibernate-A-How-To-Guide--Part.aspx
It is still in very early stages, but we can already see some really nice syntax.
I am looking for contributers, so feel free to take a look at the source and leave it in a better shape.