SmartSleep is a preference pane that dynamically sets the sleep state of your macbook (pro).

4 states available for you to choose :

1. sleep : machine will go to sleep only (saves state in RAM only, battery keeps RAM contents)
2. sleep & hibernate : machine sleeps and hibernates. (default)
3. hibernate only : machine will go to hibernate only. (saves state on disk, battery will not be used)
4. smartsleep : lets your macbook (pro) just sleep while the battery has a high level. If the battery level drops below a certain point ( default is less then 20% or 20 minutes ) it will switch to sleep and hibernate.

Download HERE

Ok. Have fun with it.