Brent Simmons, maker of the excellent NewNewsWire, linked to Mike D's Virtualization Blog for manually configured how Intel Macs go to sleep, specifically changed the default (suspend to RAM + hibernate to disk) to the old PowerPC based Macs style (suspend to RAM), aka Fast Sleep. Brent then linked to SmartSleep, which is a preference pane that puts a GUI around configured the sleep options that were previously only available in Terminal, and implements SmartSleep. This setting configures OS X to use suspend to RAM when the battery has a strong charge, and turns on hibernate when it drops below a threshold. Sweet!
If you are positive you don't want to use hibernate, you can disable it and then get some disk space back (file size matches much RAM you have installed back).
- Close System Preferences
- Open Terminal
- Type cd /var/vm
- Type sudo rm sleepimage