if you search, there are quite a few threads about battery life.
If you are running a stock rom, "no push internet" and "dynamic resource proxy" will help your phone last a lot longer.
found here
http://forum.ppcgeeks.com/showthread...=free+ram+cabs
also goto the "phone" settings and switch it to "CDMA" instead of "Global", unless of course you need GSM for some reason.