We were having similar issues, that caused excessive drain of the battery, which were corrected in 3 ways.
1. We uninstalled a program, NeoOffice, that was not compatible with Lion, for which Activity Monitor indicated it was using over 100 % of the CPU's capacity. The NeoOffice web site indicates this incompatibility, and thus we now are using iWorks. Likely there are other such programs that people should check using the Activity Monitor and the program's supplier for information on compatibility.
2. The System Report generated by the System Information program in Lion indicated that my battery had a lot less capacity than I thought it should have, and it also said I needed to service the battery. I fully charged the battery, and then after a few hours, I ran a battery calibration: Operate the computer constantly off of the battery until it closes itself down and blacks out. Let it sit for at least 5 hours blacked out and not connected to any charger. Reconnect it to the charger 5 hours later and fully recharge it. At this point, I still got the message that I needed to service the battery, but there now was a greater battery capacity than before.
3. Finally I solved all excessive power draining and the message that the battery needed servicing by resetting the SMC (System Management Controller), http://support.apple.com/kb/HT3964. Shut down the computer, disconnect it from the power adaptor, remove the battery, press the power button for 5 seconds, put the battery back in the battery compartment, reconnect to the power adaptor, and restart the computer.
Results: No more excessive draining of the battery, and the System Information now says the battery's condition is normal. Also I now have a really good charging capacity of the battery.