I use Windows 7 RC that is publicly available on a desktop computer. I am confused why does Windows 7 team let user either sleepor hibernate, but not both. Users have to go to control panel to change their mind. I think this decision might be friendly to novice users who could not tell the difference between sleep and hibernate, or do not change between the two frequently. But what about power users? They want easy control of sleep/hibernate type and hate to change it in control panel.

If you have "Allow hybrid sleep" enabled, then you are using both sleep and hibernate at the same time.You can't actually do both at the same time (I think the laws of physics doesn't allow it), but in hybrid mode, your computer is sleeping but if you turn off the power, the computer will wake up as if it was hibernating.

Hybrid sleep (hibernate after a certain peoriod of time since sleep)is a good idea but I guess it may consume more battery power than hibernate from the very beginning.