I doubt anyone truly knows if this works or not. I've heard so many conflicting arguments that I have no idea what is true and what is not. All I can say is that I've tried this once. There was a similar thread like this a couple months back. I put a small nugget in the micro for maybe 20 seconds and smoked it directly afterwards. I remember the smoke felt a bit smoother and the high was a bit 'lighter' in my opinion. The bud was some stoney indica, and after microwaving it, I got more of a sativa buzz.

No significant change in the potency though. Not that I noticed at least...