Bump. Go to the Market and search "SystemPanel App." Before I bought this app, I was firmly in the Task Killers are required crowd. But once SystemPanel App showed me what the Android OS is actually doing, I realized that Task Killers should be used VERY judiciously (e.g. poorly coded 3rd party apps). Just because an app is "running" doesn't mean that it is using memory.
I'm starting to think that the "low-tech" components of the EVO (the radios) are the primary culprit of battery drain. Not the OS...