Just some data:
My phone has been on for 10 hours, and it's at 70%. Under battery usage, display has been on for 2 hours, I've spent about 20 minutes on the phone, and most of the time the display was on, I was either browsing the web in the android marketplace on 3G, so a fair amount of data transfer. Couple games too but I don't think they amount to much.
All radios on (I leave Wifi and Bluetooth on even when I'm not using them), push email, and my twitter/facebook updating every 30 minutes. I'm not near Wifi so any data is over 3G.