This is an interesting use of the iPhone to act as a sort of remote trigger and monitor for your DSLR. It’s not quite as useful for video as it is for still but as more folks are mixing it up between stills and video at once in the studio, it could come in handy. Besides, let’s face it, who doesn’t like using their iPhone in new and cool ways. Check out DSLR Camera Remote for more info. $19.99 is a bit steep for an iPhone app, so there’s also a LITE version.