This is fantastic. I love how the Raspberry Pi is getting used in hardware hacking so much. It's ideal for it.

So far my efforts have been limited to hacking electricity and gas meters but this microwave is much more complex. I gave a talk on this last night at the HN London meetup. Slides will be online at http://unop.co.uk/dev/raspberry-pi-electricity-monitor/ soon. The videos will be online soon too I hope.