t.column :admin, :bool, :default => false, :null => false

>> user = User.first
=> #<User id: 2, login: "matt", name: "", email: "google.ninja@no-spam.com", crypt
ed_password: "c6740f820b4cbf6e3d88188719f23cd3053a54f0", salt: "5629f5ee09f51543
a7d64dd903b8d9e53aa43a24", created_at: "2009-04-26 23:08:05", updated_at: "2009-
04-26 23:10:38", remember_token: nil, remember_token_expires_at: nil, admin: "t"
>
>> user.admin?
=> true
>> user.admin = false
=> false
>> user.save
=> true
>> user = User.first
=> #<User id: 2, login: "matt", name: "", email: "google.ninja@no-spam.com", crypt
ed_password: "c6740f820b4cbf6e3d88188719f23cd3053a54f0", salt: "5629f5ee09f51543
a7d64dd903b8d9e53aa43a24", created_at: "2009-04-26 23:08:05", updated_at: "2009-
05-06 03:32:23", remember_token: nil, remember_token_expires_at: nil, admin: "f"
>
>> user.admin?
=> true

t.column :admin, :boolean, :default => false, :null => false

t.column :admin, :boolean, :default => false, :null => false