Ayende, one of the active bees behind the NHibernate portfolio, has a nice review of Hibernate Search in Action on his blog.
By the way, Ayende has ported Hibernate Search to .net : NHibernate.Search. I don’t think there is documentation specific to the project but the Hibernate Search documentation is just as useful.
I don’t know Ayende personally, but I can only admire someone that blogs more that I can tweet and still have a full time job 
