I finally picked up an iPhone 4 last Friday, and one of the best things about the new handset is the beautiful shots I've taken with the camera. I'm not a professional photographer by any stretch, and people who have actually done tilt-shift photography might have a whole lot of bones to pick with the "'shopped" version of the technique, but I've already had plenty of enjoyment from TiltShift Generator Free. It's one of a few apps on the store that will edit taken pictures to give them the short depth of field and selective focus that creates the effect. The aptly named TiltShift and Tilt Shift Focus are two other (slightly more expensive) options, but TiltShift Generator Free worked great for just messing around, and it has the added bonus of being completely free.
With the free app, you get options to blur or "vignette" (that's the shadow effect seen around the outside frame) the images, as well as adjust the saturation, brightness, and contrast. Once you save the image, you can put it back on your photo reel or export it out to email, Twitter, or Facebook. Getting the paid version for 99 cents allows a higher resolution for output, but as an amateur just having fun, I had no issues with the free version.
Again, if you're a photographer who knows his or her way around Photoshop, something like this probably isn't what you need; you already know how to dive in and edit pictures, and your best shots probably aren't taken with an iPhone anyway. But as a super casual photographer who likes the tilt-shift look and playing around with the iPhone 4's great camera, I really enjoyed this free app. It's definitely worth a download.