ICS is currently obliterating the battery on my Nexus S. 'Android OS' is keeping the device awake according to battery stats. A common issue if the xda-dev forums are anything to go by.

Hopefully this isn't by design or I might have to go back to GB.

I've also found that the messaging app doesn't deal with contacts whose number isn't prefixed with +44 very well. I've had to go through all of my contacts and add +44 to those that don't have it otherwise the messaging app doesn't recognise the number. I've not seen anybody say anything about this on xda-dev though so maybe something just went wrong with my contacts database.