The battery used to last about 24-36 hours with medium use (3G on 24/7, wifi and gps on demand only, auto brightness, syncing and a weather widget active, some voice calls and a bunch of SMS/email going back and forth daily). Hopefully there will be an improvement
Oh and that's on the latest 2.1 from SE.
Edit: well, second time around it stayed on 100% but seems to be a bit better, going down around 1% per hour sitting idle. Used to drain 2-3% per hour when idle. Will try the same thing again in a few days and see if I can get any further improvements.