[Anonymatt]

Are you sure you don't have any programs "auto updating" and connecting to the internet? I know that at least the Pocket Express, Instant Messenger, and weather update apps would do that (even when I thought I had them off, and even after a soft-reset, they'd still connect to the internet. I had to manually disable auto updates, and made sure I hit "sign out & exit" instead of just "exit" on the IM). Once I had all that turned off I went from getting only ~10 hours max battery to getting about twice that.

Since then I've hard reset, and I'm slowly installing programs and changing settings/etc and monitoring battery draw, and I've been able to get:
2-3 days with minimal use
~2-3 hours talk time (going from 100% to 0% while on the phone, or of data use)
~ 10 hours of "usage" (playing around with non-phone, non-data parts of the phone, with the screen on)

Unfortunately the phone/data uses a LOT of battery power, and just 1 hour of phone usage will cut the standby time (just being in my pocket) down by a full day. That's why I say to make sure that NOTHING is connecting to the internet that you don't want to.