As ORM tool, NHibernate provides everything I need for my applications. I am kind of still wondering what you as nhibernate users use for the business layer? In reality we need to represent our business model through two-way bindable collections, mobile business objects, features like is dirty, undo changes, etc. What tool do you use for business layer together with nhibernate? I am familiar with CSLA framework, but I am not sure how will they match together? What are your recommendations?

Thanks,
Goran