Have an iPhone, a Nikon DSLR, and want them to play together? BlueSLR has the solution for you. Their new Bluetooth dongle plugs into your DSLR and control shutter release, adjust exposure length, and use GPS tagging all from an app on your iOS device.
Compatible with the iPhone 3G and above, second gen iPod touches and above, as well as iPads, this setup uses Bluetooth connectivity and works up to 300 feet away. Only Nikons are supported at this point, but Canon DSLRs as well as Android and BlackBerry phones. The dongle costs a cool $149, so it's definitely not the most budget accessory in the world. But hey, you're used to these prices buying toys for your DSLR, right?