And one thing I noticed after the latest OTA update to 2.17.651.5 is that this Power Saver feature seems to have gotten an unannounced update, as well. As you can see from the screenshot to the right, at the very least it's gotten a UI update that makes it a bit more clear exactly what it's doing when it gets kicked on automatically. Aas long as my memory serves me correctly, and I hope it does, I don't believe Power Saver was previously quite so detailed in exactly what actions it performed to help save your battery.
This is a small update, I'll give you that, but it's little things like this that set the EVO 3D and HTC Sense apart from the rest.