It looks like Triggertrap is getting some competition. Like that product, ioShutter is a remote-control app/device that allows you to control how your DSLR takes photos, via your iPhone, iPad or iPod touch. The app allows a camera (which is hard-wired to the phone) to be triggered in a number of ways.
In its single shot mode, ioShutter can be used to take photos simply by touching a control on the iDevice’s screen. However, it also incorporates a motor drive function, timer, time lapse, sound trigger, movement trigger, and bulb mode (where the shutter remains open as long as the user dictates). Those modes can even be mixed, so you could for instance arrange for the camera to start taking shots in time lapse mode, but only once the app is triggered by a sound.
The system currently works with Canon cameras, along with some models of Samsung, Hasseblad and Pentax. A version for Nikon should be coming soon.
The app works with iPhone models 3 and up, 4th-generation iPod touch, and all iPads. Prospective users can download it for free from the App Store, to check out its features in more detail. If you want to actually use it to take pictures, however, you will require the dedicated camera cord. Although prices currently aren’t available on the product website, that cord is currently selling at Photojojo for US$70 ... which is significantly more expensive than the Triggertrap offering.