I am using mac os x snow leopard. Is there a way to hibernate? also any keyboard shortcut?
Mac OS X (from 10.4) after going to sleep will write the memory content to disk (safe sleep). After the blinking white led stops the "hibernate operation" will be completed.
If power is still available your Mac will wake up instantaneously from memory. If power (and the memory content) was lost your Mac will take a little time more to wake up (from hibernation) since the memory content has to be read from disk.