I am working with NHibernate, and a few code generation tools. MyGeneration is one and SmartCode is the other.
This question has been asked before, but I have looked
I was using Adapdev's Cudus in the past and now I'm using NConstruct (http://www.nconstruct.com) because I need also application generation, not just NHibernate mapping files.
It doesn't support SQL 2008 and I've contacted them about this issue because I also plan to migrate from SQL 2005 to SQL 2008 in the near future. According to their response newer versions will support it but I don't know when. Maybe more of us need to push them to get SQL 2008 sooner. Otherwise I like this tool very much.