I assume most people are using Googles Email Address to sync/use the phone.
Well get this, when you use it, it automatically signs you into Google Talk.
TURN IT OFFF. its like havin AIM always on, major battery hog.
"Google Talk
When you sign up for the Google Market or Gmail with your Gmail account information, you are also signed in to the Google Talk instant messaging application. The Talk application tracks the presence of your Google Talk contacts in order to let you know who is available to instant message. Each presence change uses power, even if you do not have the Talk application open.
If you do not use Talk on your device or do not mind if it is only operating when you actually have the application open, then you can eliminate this extra battery consumption:
1. Press Menu then tap All apps > Talk > Menu > More > Settings
2. Uncheck the automatically sign in box.
3. Make sure you exit the application by going to Menu > More > and selecting Sign Out
4. In order to again receive Instant Messages through the Talk application, all you'll need to do is open the Talk application again and it will automatically sign you in.
Note: Make sure you always exit the application by selecting Sign Out to reduce battery consumption. Exiting the application by use of the back or home keys will not sign you out and battery life will not be improved."
Support - Article
Also remove it from Running Applications in your Evo Phone Settings. I dont think it shows up in the Advanced Task Killer list. I removed mine since the whole debate over using a Task Killer or not, so im trying to do without.
I also havent tested this, but I figure its worth a try. It's like AIM, so it must be pretty strenuous on battery. Let me know though!
I should change the title of this thread to "I Found Out What
MIGHT be Killing Battery Life."