A new module to assign roles by cron after some time after registration

I was in need a module, which can add a new role to a user after some time after registration for the site www.afportal.ru. I payed for the module, and it was made. If you speak russian, you can read all topic here - http://www.drupal.ru/node/35597 Now I want to offer it to all Drupal community for free (if you use this code for "Auto Assign Role", please, place sponsor site link to your module page).

Module is named "Pisatel" ("writer" in russian). Webmaster can choose role and time in hours. Module uses Cron for work.

How to set up module. Extract it in modules direction, enable. Then go to update.php, choose version 1 for the module and start update.php. It is necessary to do this in order to assign a new role to all existing users and not to burden cron. Later cron will assign a new role every hour for new users.

A smal bug was detected: the assigned role cannot be removed by admin.