Yesterday I received the book, which I have been beta-”testing” for some time: Enterprise Integration with Ruby. I think it’s a good book! I’m also happy somebody finally dares to use the “Enterprise” word. I think by now enterprises have heard of Ruby and Ruby on Rails, but are not sure how it can fulfill it’s need, or how it can blend-in with their current applications. Though the book not necessarily touches on that subject in particular, it does touch subjects like LDAP, XML, Web Services, multiple databases (for one Rails app), etc.
You can find the book here