In Rails 3, the validates_format_of is deprecated. I sometimes get annoyed with all the deprecation that goes on with Rails (and Ruby, to a lesser extent), but this one is not a big deal, and the newer way is better, IMHO.
The old way:
validates_presence_of :email
validates_uniqueness_of :email
validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i, :on => :create
The new way:
validates :email,
:presence => true,
:uniqueness => true,
:format => { :with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i
¥