longer battery life can happen if you turn off these services when you don't need them:
-Data synch (gmail, calendar, contacts)
-WiFi
-3G
-GPS
-Bluetooth
You can also improve battery by making a few other adjustments.
-Have the screen timeout after 30 seconds
-Turn down the brightness on the screen. I can see just fine with it at like 30%
You might also want to consider downloading Locale.
Locale lets you set up times and locations for different settings and changes.
For example when I get near my office Mon-Friday from 9am to 5pm, wifi gets turned off, my phone gets set on vibrate (with no ringtone) and my wallpaper changes (just because).
When I get close to my apartment, WiFi turns back on automatically.
There's also a Toggle program that basically lets you make these chanages manually without running all over the settings menus looking for them.