Today, Palantir.net is releasing several module that we built as part of our client work. One of these modules is the SWF Embed module. With this module, developers can create tools that include flash objects.
This module makes use of both PHP code and JavaScript code in order to provide robust Flash integration used in projects like the Flashy Drupal video player. But from a developer's point of view, all you need to do to add Flash support is create an object and theme it. The SWF Embed handbook page describes this process in detail (not that there is a lot to describe).
But there is a hidden gem in there that may come in handy for your non-Drupal sites (if you believe in such a thing).