After looking around the web it looks like I am not the only one getting next to no power savings with Hybrid Power and the 2XX series GPUs. In Silent PC's review of the Asus M3N78 Pro they tested Hybrid Power and saved only 5W when idle. With one 260 GTX they achieved 75W idle when in save power mode. With just the onboard graphics they achieved 38W idle.
"Unfortunately, HybridPower doesn't come even close to shutting down the card's power demand entirely. In the Save Power mode, power consumption decreased the most during video playback, 11-17W, but only 5W idle, and only 3W when the CPU was put on load. We did notice the card's cooling fan turning off when Save Power mode was activated, but the card remained fairly warm. It's evident that the card was still drawing a fair amount of power, but not so much that the card would overheat without the fan spinning."
It's like Hybrid Power is completely broken with the 2XX series GPUs, I think most of those measly 5W saved is from the fan being shutoff.