I used a Marmitek X10 for the exact same purpose. I can SSH from my phone to a small linux box running on an old eee PC, which switches the coffee machine on or off. I used a dedicated public-key for on or off, so I can do so with a single click from my Android phone without having to login or run any further command.
Works a treat! So many times I'm on my way back home and want to make sure the machine is ready and warmed-up.