My copy of NHibernate in Action arrived just before my flight to Alt.Net Seattle 2009. I've been devouring it in my spare moments.
Sure I could have read the electronic version earlier ... but I'm an old guy and I like the printed page. I am similarly challenged wading through online documentation. So I kill trees.
Anyway, this book is available in tangible form at long last ... and it's darned good. Clear, methodical, plain-speaking, and occasionally entertaining. That's not faint praise, I assure you.
Get it and read it ... especially if you're an Entity Framework fan and want to know what some of the NHibernate fuss is about.