Director Michael Koerbel of Makek Pictures notes that the short took 48 hours to create from start to finish. He's also promised to release a full behind-the-scenes video that will document its production.
It had to happen eventually. Here's the first (that we know of) movie shot and edited entirely on an iPhone 4. Two years ago we saw a music video that was shot with a jailbroken iPhone and Cycorder. Of course, the iPhone 4 ups the ante with HD video and iMovie for iPhone.
And just like that, the iPhone becomes a nice little tool for filmmakers, amateur and pro alike. It's not going to replace real cameras, of course, but you can use it to make something nice, as Koerbel has demonstrated.