I am NOT exaggerating. Here is what I did:
(1) Upgraded to 2.1 (Phone is 100% stock right now. Not even rooted)
(2) Downloaded "Advanced Task Killer 1.5.6" by Apollo Software from the market (It's FREE)
(3) Went into "Settings" of Advanced Task Killer and set some apps to "ignore". Everything else is set to "auto-kill" one minute after the screen turns off.
It is 7 PM here in Chicago. Phone had a full charge yesterday morning at 8 AM, which is when I unplugged it from the charger. Currently the battery is a 50%!!! Normally, it would have been long gone by now. I can easily go another day on this battery.
I'm stunned. Normal use too. Talking to friends, texting, and of course browsing.
UPDATE: see post #151 for clarification on "Advanced Task Killer", which is now called "Apollo Task Killer"