The person who mentioned the "Lensbaby" product for dSLRs had it right. This is not just for simulating miniatures. In fact, thats the least of my concerns. You can use this to simulate small depth of field. Cool!
You have full, flexible control of the shape, placement, and size of the out-of-focus area, with easy touch-based manipulation. Basically, you create a mask for the blur area.
At $0.99, everybody interested in photography should grab this.
Developers: you need to market this thing better!
KH-NY about TiltShift