It would be very handy if you dove into the details a little bit on exactly why you need to override GetHashCode and Equals... Do you need to override these for every entity that NHibernate persists?

Dan,

I left those details out, because I would be re-stating what the above links already talk about (specifically, the last 4 - the first two give good detail on how to properly override these methods).

In a nutshell, though, I recommend overriding equals and gethashcode on ever class that NHibernate will be persisting. My reason for this is that I very rarely, if ever, see a class that is not used in a collection (ISet) or across multiple NHibernate sessions.

The pragmatist in me says that you don't have to override it for all objects. I've done plenty of small sample apps using NHibernate, and not had problems when I didn't override these. However, in any medium to large scale system, I would rather avoid the issue by having the correct code in place immediately vs. wait until I see the issue and then pull my hair out trying to find out why it doesn't work (which is what I've been doing for the last 4 days, hence this post. :) )