Originally Posted by leftystrat
It looks like it's still pretty busy going through the battery whilst doing nothing. I think rooting may be in order, if all else fails.
I think I know why now that more info has been posted.
ICS has a feature (some call it a bug) where it tries to check with Google servers to resync any and all settings, apps, and files that may have been backed up on Google servers. For the first few days it keeps checking for data to restore. Just use it normally for a few days and it will eventually finish looking for data. If you have a 3G model, make sure you keep the WiFi connection open so it can use WiFi to download any data and save your 3G data bucket.
If you don't use Google Backup and Restore, it still spends a few days trying to connect to Google servers to confirm there is no data to download. It's annoying but it stops eventually. If you prevent all data connections, it will just keep checking for a live data connection anyway regardless of the data state, that's why it's eating the battery even in airplane mode.