A few days ago a very tedious procedure was posted for getting Flash on your iPhone. Today, thanks to the magic of a jailbroken iPhone and Cydia, you can install Frash, (the app to run Flash on your iPhone) with 3 easy steps. (Only iPhone 4 and 3GS are capable of this install.)
1. Open Cydia > Manage > Sources
2. Edit source and add http://repo.benm.at
3. Search Frash and install it.