CSSEvents is a project mainly written in JavaScript, it's free.
Adds support for CSS Transition and Animation events in Mootools 1.3
Adds cross-browser support for CSS Animation and Transition events in MooTools 1.3
element.addEvents({
'transitionstart': [Function],
'transitionend': [Function],
'animationstart': [Function],
'animationend': [Function],
'animationiteration': [Function]
});