Below is description of my changes in order as they appear in the code.
Improvement: I have added event to validate radio and checkboxes like text field just after change. Now you have to submit form to validate those fields.
bugfix: I have put field type change into try-catch because it cause errors in IE8 and 7 on some site.
It is not a bug, but it will protect validator from other errors in 3-rd part extensions.
Improvement: I have made simpler usage of radio and checkboxes validation. So far it was too
complicated. Now it is still backward compatible.
I have also added validation of multiple select list. Such field you can create with core field type of list and without this fix it would not validate as required.
bugfix: Fix of usage Hash object in isValid method which is part of mootools-more which is not being loaded with validator since J!3.
Closed as per the comment on joomlacode