Flash has come to the iPhone--or rather, the iPhone has come to Flash--thanks to a clever addition to the Javascript Runtime Environment called Gordon and created by Tobias Schneider. While the addition doesn't require "Jailbreaking" the iPhone, it does have serious limitations.

As a JRE extension it runs natively inside the iPhone's Safari browser, however it will only work on sites that have specifically incorporated the Gordon code. Reports indicate that a static image presented in flash will peg an iPhone at 100% CPU, so it's not quite ready for browsing YouTube via Safari just yet. It does support the full feature-set of Flash, including interactivity and animation, but full-Flash sites may not be viable on mobile devices for some time.

More: http://pcworld.com/article/187005/

............................................................................................