Wow. Who expected a game changing integration of the iPad into photo shoots this quickly? Nice, and obviously still in it's infancy with room to grow.
There is DSLR remote for Canons and Nikons that work much in this same way though an Ad-hoc system.
I've tried these things before, even back to the days of sending a wireless NTSC signal from a desktop to a hand held ICan Monitor and like all move around wireless, sometimes they work, sometimes they don't, but most are just a gimmick under fast pace production, unless you dedicate one single person to do nothing but tech the viewing devices.
This Ipad thing "may" be different in it's use, but at least it's a way to see a phase file on a good lcd, though I wouldn't really like clients screwing around with color and exposure, but that's just me, maybe other photographers would think that's fine.
When these hand held devices do work, everyone is kind stoked for the first 30 minutes, then they are back to the tethering stations and the portable monitors are just sitting on a table burning through batteries, or worse someone yells out hey can you go back that that other shot you know the one with the hair behind her head and let me see that?
In other words a lot of this stuff is more distracting than useful IMO and more for a client than a photographer. The photographer needs to see the shot as they are working and would be more photographer useful if Phase would just glue it on the back of their Pee systems.
Actually, I'd love to see it get back to the days where the A.D. actually looked at the set, rather than the screen, because there is inspiration on the set, reviewing everything on the screen is usually just damage control to make sure you have "that" shot, safe, but not very inspirational.
It's more a democratization of the shoot and in my view detaches the creatives from the set and if one of these devices ever gets out in the crowd, you'll never get anything shot, it will just be a million voices willing to give "suggestions".
Now the one use I can see for this is to build a bracket and mount it to the tripod leg, that way the photographer doesn't have to run over to the monitor to see the lighting set up.
Now if you really want to open up a world of hurt, shoot a job long distance. We did a gig last year where the C.D. could not travel, so we set up with a company that gave her a live view on her computer of the images as we shot. It took about 10,000 cell phone calls with stuff like, "can you move that prop to the left and can you get the model in the blue shirt to smile more. At first it seemed somewhat useful and "safe", but then you'd make the changes, call the C.D. and she's in a meeting, or on another phone call, so the crew sits, the rhythm is broken and then you get back to work.
What would have been an easy day, turned into 12 hours and a lot of opportunities were missed.
Photography is now a collaborative process, but not necessarily democratic, not if your going to produce anything interesting.
Once again, IMO.