Yes, I am writing the Rails 3 in Action book that was originally called “Merb in Action” before the Merb+Rails merger. I was approached to join the team to be a co-author with Yehuda Katz at the beginning of April and the process with him & Manning has so far been wonderful! I’ve been writing the book from scratch since the end of April and so far I have five-and-a-half chapters written with the sixth one (Authentication & Authorization) probably finishing up this weekend.
We’re aiming to get the book done published by December 2010 in both paperback, PDF and (probably) eBook-reader formats too.