WRONG
$$('.element').each(function(el){
el.addEvent('mouseenter', function(){
el.set({ style: 'border: 1px solid #AAA;' });
});
el.addEvent('mouseenter', function(){
el.set({ style: 'border: 0;' });
});
});
COOL
$$('.element').each(function(el){
el.addEvent('mouseenter', function(){
el.addClass('border');
});
el.addEvent('mouseenter', function(){
el.removeClass('border');
});
});