I’ve been playing with this on my iPhone a lot lately, and also have discovered some tools to make image calibration right on the phone easier. The photos below were taken on my phone and then worked with Photoshop.com which provides a very friendly interface for filters, cropping, and even uploading. In some these photos I’m also experimenting with some tilt-shift effects (to varying degrees of success).

Here are some cool links:

http://iphonephoto.us/
http://www.ippawards.com/
http://www.philcoffman.com/blog/photography/iphone-photography/

And some cool tools:

Camera Bag
Best Camera
TiltShift Generator