In order to save folks some of the headache I went through getting my microwave out, I thought I'd document the steps needed to remove the oven from the cabinet.
1. Remove the two small screws holding the plastic vent intake cover onto the top front of the microwave:
2. The front will now look like this:
3. Find the two retainer screws at the top front corners of the microwave:
*DO NOT* remove them yet.
4. Clear out the shelf above your microwave. You need to free the shelf veneer. I accomplished this by inserting my fingers in the power cord hole and gently pulling up. The veneer is held in place with several small brads. Be careful not to break the veneer. I wasn't able to easily remove the veneer, but could slide it up enough to get to the top anchor screws:
5. Find the two large top anchor screws and remove them:
6. Now, while holding the microwave in place by supporting it from the bottom (a second pair of hands is nice here), remove the front retainer screws. Then tip the oven forward enough to gently lift it off of the tabs at the bottom of the mounting plate.
My plan, once I get my oven replaced, is to remove all the brads, and re-secure the veneer shelf to the cabinet using small flathead wood screws. That way it'll be much easier to repeat the process if necessary in the future.
Hope this helps someone avoid some thrashing!