Redmond Pie has successfully and completely ported iMovie for iPhone 4 to an iPhone 3GS. It was originally rumored that iMovie for iPhone only works on iPhone 4 due to the exclusive availability of 512 MB of RAM. Now, you can see that the application works almost flawlessly on a 256 MB of RAM device.
If you’re interested in getting this working you will need to follow a long and tiring step-by-step guide which involved SSH skills, jailbreaking, and editing of the internal iMovie for iPhone application files. Because of this we don’t recommend it, but it’s cool for those who like to live life on the edge.