With a little help from the DSLR.Bot app ($4.99 in the App Store) for iOS, you can add an infrared trigger to your iPhone for Canon (and soon Nikon) DSLRs.
Check out the simple DIY instructions for the infrared iPhone adapter in the video below.
Phil B says
I know this looks simple but I am wondering if there are any pieces like this made all ready put together? I have an iPhone and would love to have this control but with my hands I could not make this myself.