So basically OpenWRT + "wol" package + google app engine. Write a google app engine script that takes a 'wake up machine' html form, write a bash script on OpenWRT that queries the script regularly, and run the "wol" client when you get a response. Seems useful.
I was experimenting with new technologies for this project - yes, to get the core functionality sure this would work. In this case, I wanted to make something more... complete. The communication with the device uses websockets, not polling.
MAC addresses are bitstrings typically written in hex and should not be interpreted in a case-sensitive manner. You should also accept colons, dashes, or nothing as the byte separator.
I'll look into that.
You can also use http://www.smscmd.net/ to connect your raspberry pi/arduino/<insert device> using MQTT and then you can wake your device using SMS.
Does it give you an online|offline status indication of your device?