The guys at Engadget spent the weekend putting the newly-released iPhone 3G's battery through the paces and found some fairly encouraging things. The tests, which included activated 3G and WiFi modes with Bluetooth off, data fetching enabled, medium volume, medium screen brightness and auto-brightness enabled, yielded the following results:

Music (continuous playback, large library, occasionally turning on screen): 31h 23m

Video (continuous playback, no push/fetch data): 7h 5m

Video (continuous playback, with push and 15 minute fetch data): 5h 24m

Daily data use (browsing, email, and GPS / maps): ~6h 30m

Not bad, but if you spend a fair amount of time reading news or checking e-mail, you might run low on battery power by 3 or 4 PM. The best way to lengthen battery life is to turn of 3G mode, which can prove to be a hefty drain on the battery.

How's your iPhone 3G working out for you? Let us know over in the comments or forums.