(from http://rafb.net/paste/results/PzvIYk70.html)
donp@orbiter:~/work$ rails arbug
donp@orbiter:~/work/arbug$ createdb arbug_development
donp@orbiter:~/work/arbug$ psql arbug
arbug=# create table bugs (id integer, truth boolean);
donp@orbiter:~/work/arbug$ script/generate model Bug
donp@orbiter:~/work/arbug$ script/console
Loading development environment.
>> b=Bug.new
=> #<Bug:0xb740eec0 @attributes={"truth"=>nil}, @new_record=true>
>> b.truth="true"
=> "true"
>> b.truth
=> true
>> b.truth="true"
=> "true"
>> b.truth
=> false
>>
bitsweat pointed out that
ActiveRecord::Base.generate_read_methods = false
fixes the problem
(can be seen in http://rafb.net/paste/results/44SWZf67.html)