Rails 3 is a lot of things. It includes a rewrite of ActionController, Railties, and the underpinnings of ActionMailer and ActiveRecord. It extracts the core parts of ActionController and ActiveModel for reuse by plugin developers. And it makes every Rails “framework” a plugin, so extension authors can easily replace ActiveRecord, ActionMailer or ActiveResource, leaving nary a trace of the old frameworks behind. In other words, there’s a lot to catch up on. Yehuda will go through the important high-level changes, giving you a starting point for digging into the improvements the Rails team has made for Rails 3.
Yehuda Katz is a member of the SproutCore, Ruby on Rails and jQuery Core Teams; during the daytime, he works as a framework architect at Strobe. Yehuda is the co-author of the best-selling jQuery in Action, the upcoming Rails 3 in Action, and is a contributor to Ruby in Practice. He spends most of his time hacking on open source—his main projects, along with others, like Rubinius, Thor, Handlebars and Moneta—or traveling the world doing evangelism work. He blogs at http://yehudakatz.com and can be found on Twitter as @wycats.