I had a similar need a while back and ended up building my own. Specifically, I wanted a wireless release that worked with my iPhone. I've since polished it up into a nice little product:
Shutterbug Remote
-Wireless using bluetoothLE (no wifi hotspot, no IR line of sight) with >100ft range
-Advanced controls like long exposure, intervalometer, ramp, mirror lockup
-VERY small and light
-Free app
Feel free to contact me on the thread or directly via
[email protected] if you have any questions.