Alex has just released Base4 version 2.1. 

I haven't been following the progress of Base4 that closely but it appears that it has matured into a very stable and innovative product - take a look at the 15 minute video if you doubt my word!  I can't see how any other product could be simpler to use than Base4.  It's awesome.

Alex: it might be a good idea to do some benchmarks like the NHibernate v ADO one I saw recently - sorry can't find the link now.  It would be interesting to see the comparison.  I'm thinking that Base4 would stack up very well against NHibernate :)