Been programming with Rails for well over three years now, and only now had the need to know what an attribute was before you changed it.
2.2.0 :007 > c.first_name
2.2.0 :008 > c.first_name = 'Johnny'
2.2.0 :009 > c.first_name_was
May be old hat for a lot of ya, but awesome when you get something for free.