I think Pagemakers wrote all over this forum about it
Also it seems that battery usage only high in areas with 3G coverage.
This is definately not as simple as having poor battery life, or being in a 3G area. My coverage at work is typically 1 bar on 3G Voda, and my phone sits on this all day, every day. I typically make ~35min of calls a day, and heartbeat around 100k of data. I charged my battery Friday lunchtime, and I'm now down to 1 bar (it's now Tues evening).
I have, however, had a day when the battery went from full to 1 bar in about 14 hours. I have no idea what I did differently, other than maybe travelling around a bit more than usual.
The other think I have noticed is if you reboot the phone, you often "gain" a bar of battery, so it maybe the monitor is buggy- check to see how long it is before your phone actually runs out and switches off.
Finally, turn off "receive all beams"- this saves battery, and turn off bluetooth when you're not using it (mine is always off unless I'm in the car).
Hope this helps a little