I have been slowly testing my iPhone and it seems clear that the battery life is extended if WIFI is turned OFF. In my simple tests I charged my iPhone fully with WIFI on and the phone lasted about 34 hours with moderate phone use. With the WIFI turned off I am still going with over 60+ hours of moderate use.

A month ago my Blackberry 8700 died and I borrowed an Nokia N80 demo phone from the Flash-Lite team. The N80 I borrowed was terrible and battery life was 24 hours tops with a full charge. I thought surely something was wrong but it turns out that the WIFI chips are very power hungry and simply turning the WIFI off on the N80 returns battery life to normal. When I started to see shorter battery life in my iPhone, I explored the WIFI to see if that had a measurable effect. Bingo!
I am also curious if the WIFI density has an effect on battery life as well. I live in San Francisco and my iPhone detects over 2 scrollable pages of networks. I am not sure at the chip level this would have any effect on battery life.
So turn the WIFI off in your iPhone and your battery life will be extended.
Cheers,
Ted :)
DIGG IT! 
I guess in order to give this somewhat of a Flex slant... Will Flex apps run on the iPhone?
That is a question that only Apple can answer. Regardless my battery life is longer.
Ted :)
I suspected and feared this was the case. It's a major for 2 reasons...the EDGE is painfully slow at best! And it roaming with it is insanely expensive. So it's a pain in the ass to always switch the wifi on and off:( iPhone is nice but still has a ways to go!
On the same note, having bluetooth on will also run your battery down faster, so if you are not using bluetooth turn it off to increase battery life.
Man Ted...my Dash lasts about 4 hours with wifi and bluetooth off. :-( I know 4 for sure because it usually dies when I'm on the golf course (which is usually 4 hours). :-D lol
That's with phone use and non-use. I am dang near envious of my wife's sidekick which can last days. All that to say...24 hours would be PERFECT! At some time in 24 I'll sleep so it'll recharge so if I could get 12 hours I'd be good.
I bought the xtrememac incharge for charging in the car then when at work it's plugged into my mac... so im never out of juice.
Collin, Just turned bluetooth off as well.
Thanks,
Ted :)
For a GSM phone, the standby consumption is around 3 mA or less. However, if WiFi is turned on, even without any usage WiFi alone can consume up to 6-10 mA. This means that you are going to see a huge reduction on the standby time. Neither Nokia nor Apple has magic here.