A few years back I used AASM. More recently, I just build state functionally by hand on an as needed basis. So I check out rubygems.org and low-and-behold there are many offerings.
Here is a sampling: http://rubygems.org/gems/state_machine http://rubygems.org/gems/aasm http://rubygems.org/gems/acts_as_state_machine http://rubygems.org/gems/statemachine or all of them: http://rubygems.org/search?utf8=✓&query=state+machine
My question is… which one is considered the current “standard” in state machine gems for rails 3?