Many people find the power saving features of Windows Vista annoying. Example - at the company I work at, we use Dell computers, now preinstalled with Vista Pro. The laptops, and even the desktops come configured by default to not actually shutdown, but rather to save your session, files, then go to sleep. Many people like this as the shutdown process can take too long (in their minds). This can be very bad though, if group policies are in place (example, log off scripts). They will not run if you are not actually logging off.
Also network settings should be considered. I know people who just close the lid on their laptop and run out the door carrying it. Problem? Depends. If they hook it up at home, and connect via VPN, then close the lid for the night, then turn it on again (wake it really) in the morning, then bring it to work, well network settings are bound to get mangled. Example - DNS settings from home may still take precedence over the work DNS, causing a slowdown or failure to connect to the file server.
I have seen this happen many times now, to the point where I always ask laptop users, "did you shutdown completely or just go into sleep mode"? Yeah, a reboot almost always cures connectivity issues, but an ipconfig /release, /flushdns, and /renew works frequently too.
So, in order to cut down on greenhouse gases and save energy, hardware vendors, OEMs, and Microsoft, along with many other corporations trying to increase that 'GREEN' image, are implementing hard core power saving features. Be careful though - your clean ways may interfere with your productivity.