Control your DSLR from your iPhone, iPad, or iPod Touch using the ioShutter Camera Remote and ioShutter App. The ioShutter App (free and paid) supports six different modes: standard trigger, motion trigger, sound trigger, time-lapse, timer, bulb, and modes can be combined. Most of Canon’s cameras are supported, and it sounds like a version for Nikon cameras is in the works.
The ioShutter Camera Remote competes with the successful Kickstarter project - Trigger Happy camera remote. Remotes like these are going to replaces the standard remote switches most manufacturers offer – the added functionality you get in the supporting Apps makes it an easy choice, and you don’t have to pay a whole lot more for the added functionality.
Update 05.08.12: Camera’s from the following manufacturers are supported by ioShutter Camera Remote: Canon, Hasselblad, Pentax, and Samsung. Nikon coming this summer. Compatibility details available on the ioShutter website.