Someone correct me if I'm wrong, but don't you *want* a higher percentage of 'cell standby'?
Think about it for a minute: if you've used some battery and want to break down how it's used, then 100% of that usage being 'cell standby' means that none of the battery was used up by background processes. This is a good thing: it means they're not wasting time in the background and that your only energy consumption was to keep the cell antenna online. In fact, if 'cell standby' use was low, that means that everything else is using up battery like crazy.
The real deal is that when you add up the numbers, you have to come out to 100%. If you split a pie into three pieces (three processes using battery), you still have a whole pie between them (100%), so if you only had one big-ass slice that was 'cell standby', then that would be your 100% -- all of the energy used was for cell standby. Cell standby is a constant... as long as your phone is listening for SMS messages, phone calls, etc., your cell is using battery. It's probably not using more battery now than it was before -- it means your other processes are using less.
Hope that helps clarify!