2g was dead in my area this week. I noticed 3g was consuming lots, killed xchat, didn't improve much. Then I killed openvpn, it was doing a ping every 20s. That brought traffic down to like nothing, except for this one guy who thought I'm an edonkey server and kept knocking on a port regulary. Reconnected, got a different IP and now power consumption was manageable..

The thing to remember about 3g is that a single packet of internet traffic consumes almost as much power as full tilt download for 5s... In other words, any traffic keeps the radios active for quite a long time after, which makes all sorts of low rate traffic like IM consume large amounts of power.

It's operator dependent, and I'm told my operator has particulary bad configuration for always-on 3g...