Sadly, I now have to update my story. It seems that a nineteen year old woman from Lanexa, Virginia was charged with allegedly murdering her one month old baby in a microwave oven on September 23, 1999. The apparent claim is that Elizabeth Renee Otte had an epileptic seizure, became confused as a result, and placed the baby in the oven. Epileptic experts and prosecutors are not buying this claim, however. It should be interesting to see where this story goes.
Cats being nuked is a totally different story.
There are enough whackos walking the streets out there that we can be certain that someone must have tried it at some point in time. I have had enough students in my classes over the years that have done similar stunts, so I am positive someone has tried it somewhere. I'll leave that for you to decide.