I don't know about microwaves, but at least one refrigerator for sale here has a computer screen that can log on to the internet, called a "net fridge".

Here is an article about a prototype web enabled microwave (and you thought you were being silly!.)

http://www.cnn.com/TECH/computing/9809/14/microwave.idg/

Can you set the cooking time for 24 hours or more?

Will you be running it at full power or throttling it down? Do not heat maple syrup while at full crunching power or it will spatter out of the container.

If you open your microwave it will have to go back to the last checkpoint to continue. Food may become overdone in this situation.

If all of the water is boiled out of the proteins, they may not fold correctly.

An oven has a "firewall", but I'm not sure that a microwave needs one.