My not quite powerful enough cell phone went for a swim yesterday - lets just say there was no moment to ponder the idea of taking it out of my pocket.
Picked up the new Samsung Galaxy IIIs and the Chainfire DSLR controller for EOS cameras.
Another giggle and snort moment to be able to drive the camera from the phone, even if tethered.
Manual focus, auto focus, all the settings that are available from the Quick menu for the mode wheel position (at least on my T3i), and of course take a picture, view it on the phone screen (which the galaxy has a nice one)
I can see it making low level macro shots much easier, etc. It doesn't appear to be fast enough to use as a remote monitor for movies - but it is a great start.
I have downloaded the Magic Lantern android app but not have a chance to play with it as of yet.