We are removing all the deprecation warnings that we introduced in 3.2.x. We have decided to stop introducing API deprecations in all point releases going forward. From now on, it'll only happen in majors/minors.

这个版本去掉了 3.2.x 里面所有的 deprecation warnings，Rails 开发团队在各个小版本 (a.b.c - c 所在位置的版本号变化) 的升级过程将不再会有弃用 API 动作，这类动作只会在前面两个大版本升级的时候才会有。

http://weblog.rubyonrails.org/2012/8/1/ann-rails-3-2-8-rc1-has-been-released/