i've got the same issue with the baseband_xmm_power wakelock. It first appeared after flashing JB on my (at this point) unrooted device.
Short descripiton of my experience so far:
- Disconnected fully charged phone in the evening. WLAN on, everything else turned off.
- After some hours a massive drain started and stopped a few hours later.
- The rest of the time the drain seems normal.
I haven't touched the phone a single time within those two days and ten hours of waiting, so there was absolutely no userinput or anything.
The small drop on the right is activity, so thats no issue.
I hope this helps figuring out what the problem is so we can solve this soon.