Auto turn Data off when you lock the blackberry?

Is there an app that does this:

- When i lock the blackberry, it turns of data/internet services (not radio, so i am able to get called).
This would save a lot battery :eek:

- When i unlock the blackberry, it turns back on the data/internet services.

Who can help me out, i really want this :(

I *think* that S4BB's battery app does this... not 100% sure that it does or that it works though.