(Cross-posted from http://blog.projectxtech.com/2009/08/06/rails-3-updates/)
Rails 3 is a rewrite / merger with Merb, and includes Yehuda Katz, Merb lead developer working on it full-time. Here are some posts which were published recently:
http://yehudakatz.com/2008/12/23/rails-and-merb-merge/
http://weblog.rubyonrails.org/2009/7/30/community-highlights-yehuda-katz
http://yehudakatz.com/2009/03/06/alias_method_chain-in-models/
http://www.engineyard.com/blog/2009/6-steps-to-refactoring-rails-for-mere-mortals/
There are lots of lessons and techniques in ruby, rails and general programming to be learnt from these posts. Enjoy!