Digitally tilt-shifting (the process of selective focusing to create a faux miniature scene) was all the rage online a couple seasons back. Now there's an iPhone app that purports to offer the same with snapshots taken with your phone's camera (or use via online app)...
In our experience, TiltShift Generator for iPhone is more adept at creating vignettes and minor depth of field changes to a photo rather than a convincing tilt-shift effect using the radial and linear blur options, but is also dependent upon photo choices.
Try the online version and if you like it, you can purchase it as an iPhone app for .99 cents and then you can directly email your quasi-miniaturized photos to friends directly from the app (or Twitter it).
Thanks to reader Quincy for the link!