Just chiming in here: Today was my first whole day with the Evo. Took it off the charger when I first woke up this morning, but then while I took my morning shower I plugged it back in just in case... So I pulled it back off the charger before heading out for work at 0830, with 97% battery showing (via batterytime lite; I just put in that I have a 1500mah battery since the Evo isn't listed yet).
I have 4G off because I'm not in a 4G market; I have WiFi off because at the office they're bitchy about personal devices on their wifi, plus I use the phone more for 3G services like SMS than anything else. I had GPS off at first but then read that it doesn't use lots of power, so I turned it back on. Oh, and my brightness is set to automatic. EDIT: I also leave Bluetooth on because it's paired to my car and I never remember to turn it on and off when I get in or out of the car.
Over the day I flipped thru the market looking for apps, downloaded a half dozen apps, took a couple pictures, played with layar for 5 minutes, texted a normal day's conversations with my GF, made and took 3 or 4 calls, played a round of one of the trivia games I DLed, googled a few things for people, shot a bunch of fake shells off with SchottGunn, and additionally had to do all the obligatory showing it to the people at work and letting them play with it.
It's now about 10:30pm and I have... 22% battery left. So, it's no superphone on battery for me, but I don't think it's all that bad.
That's my initial input on the topic. =0)