Link

An enterprising photographer has managed to tether his Canon 5D Mk2 to his iPad...

All you need is:
1. Older model Eye-Fi card
2. Synchrotech CFMulti adapter
3. MyWi app
4. ShutterSnitch app

If your camera uses an SD/SDHC card you can dispense with the multi-adaptor and you may be fine with a newer Eye-Fi card but it depends on the camera.  However, it seems that it can be done.

Follow the link for more information and a video on Jesse Rosten's blog. 

Excellent!