iMobileCinema is a currently buggy app for jailbroken iPhones that works "most of the time" on 2.x iPhone firmware, giving you flash support in sites like YouTube. It kinda works.
Just add this to your sources d.imobilecinema.com in Cydia and install iMobileCinema. Again, this is only for Jailbroken phones, but it will give you Flash in Safari. We haven't tested how unstable it is, so try it only if you don't need your iPhone to be not crashy. [iMobileCinema via Spaziocellulalre]