I have just commited the full implementation of NHibernate Search. No documentation yet, but there is the Hibernate Search documentation, which matches nearly 1:1.
You can get it from NHibernate trunk:
It probably won't be released with NHiberante 1.2, but it would work with it.
This is great stuff! Thank you.
Is there any plans of incorporate this into ActiveRecord?
By necessity yes,
since I am using Active Record in my current project.
Is this somewhat an alternative to the free text search modules that come with some of the databases?
Yes and no.
Usually full text searching in the databases is an add on, and it requires more complex setup / backup procedures.
It is usually limited to a single column, most of the time.