I really wish we could get more information on this.
I've done the airplane trick, dialed *228, and even changed to CDMA using *#*#4636#*#*. I locked my phone at around 1 am this morning, and didn't touch it again until 11 am. After 10 hours of just sitting there, with Mobile Network, Wireless, GPS, Syncing, and Bluetooth all off, I went from 90% battery to 60%. 48% of battery was cell standby. I would be very happy with only losing 30% of my battery after 10 hours of usage (ecstatic really), but it literally was sitting there doing nothing. I turned off everything I could, other than leaving it in Airplane Mode, I don't know what's wrong.
The specs say the phone should get ~150 hours of standby time. Based on what I'm seeing, it's more like 35 hours. This was my 4th full charge, so it should be pretty close to broken in, and I'm using JuicePlotter to track my battery levels.