After updating to 4.1, battery life of my Galaxy Nexus is very short ( about 10 hours without heavy use ).
Unfortunately i found that Google Now is the evil ... Disabling it boosted battery's life up of about 50%
Why? Most is for geo services used for position history.
Another battery killer is google plus sync.
Try turning both off, and see the difference :)
To stop Google Now:
Click Google search bar (or enter Google Now service), click on the right bottom button -> settings
Click Google now and toggle to off. Turn off localization service too.
To stop G+ sync:
Go to the phone settings and scroll down to the account section, then press on G+ and disable sync.