I've had my Liquid E for three weeks now. For the first two weeks, battery life was really bad. I had to charge it around dinnertime, and I hardly got any calls. No apps running in the background, no task killer, nothing. I even turned off GPS, switched to 2G, and shut off data.
Now, I've got everything turned on, and it lasts me from the time I unplug in the morning (usually around 8am) until I go to bed (around 11pm) with juice to spare. I'm rarely below 20%, unless I get busy with Angry Birds
ETA: I'm running eclair. I am not tech-savvy enough to mess with my phone, so I'm waiting for Froyo to be released from my provider.