I had this issue, excessive battery drainage from a week ago on my Sony Live with Walkman. I charged the battery the whole night and it was dead on the afternoon. At the battery discharge screen always the top consumer was Android SO, which I didn't remember seeing before. I tried everything I found on forums the battery calibration procedures, removing all syncing apps, turning off the 3g, wifi and bluetooth, and the battery was still draining fast, brightness reduction to minimum.
The last thing I wanted to do was a factory reset, but it was what solved it for me... I mad a backup of everything, musics, photos, contacts, and with the reset I selected to clean SD as well. I'll try to send the screenshot of the battery drain, and you can see there's no consumption of Android SO (the icon was like two gears connected with a belt.) Sorry the screen is in portuguese, but I'm sure you can relate with the icons.
Maybe there was an specific app messing with the phone.
Now started the night with near 60% with wifi and BT on, and near 11:00AM still have 40%.
If you think battery is draining fast and top consumer is android so, consider doing a factory reset. Worked for me...