mine can last about 20 hours (& about 3 days if i don't use anything except answering/calling.)
approx. 30mins of phone calls, 1-2 hours of gaming &/or listening to music, 20 SMS, battery widget & lookout security is enabled 24/7.
WIFI, 3G, Bluetooth & Auto-sync are disabled unless i wanna use any one of them. i also use the 2G network instead of 3G (goto Network settings).
brightness is about 40%.
some background apps consume alot of battery power, so choose an app which doesn't drain out your battery more than usual...
& always kill tasks once every 10-15 mins or after using the phone & apps.
force-kill the app(s) if it keeps starting every 3-4 mins (if it doesn't work in Task Kiiller- goto manage Applications, select the app & click on force stop).