In my case, it's media (sometimes displaying as android.process.media) that's killing my battery. I'm lucky to get 10 hours between charges since JB (it was 2 or three times that under ICS). When I first turn the phone on, the media component is small, but within an hour it's at 50, 60, or even 90% and has kept my phone awake the whole time and sucked out 10% of the battery - and I'm not doing anything with it during this time!
Yeah Lois I agree with you! They did screw something up in this update. No one had this problem before updating. Right now, having just unplugged my phone, media is at 0 and the system mediaserver process does not even show. But like you said just give it a couple hours. I do get a lot more than 10 hours out of my battery so not making it thru the day is not an issue with mine. But it still grates on my nerves that something is not running quite right and I have been driving myself buggy trying to figure out how to stop it. I think we can be pretty sure that Moto/Verizon/Google won't bother to address the issue.