For those of you who read that the Lumia 800 had a battery issue and wondered if Nokia was on top of it, they are. There is an update coming next month that will take the battery from 1300mAh to 1450mAh.
According to Nokia Support boards:
We understand that some people have expressed concerns about battery life on the Nokia Lumia 800. Early investigations show that most people are enjoying the full Nokia Lumia experience without any problems and we have not been able to identify a single root cause that would lead to erratic battery behavior at this stage. A software update in early December will make some improvements to power efficiency, while a second update in early January introduces high voltage charging, increasing the Nokia Lumia 800’s battery power from 1300mAh to 1450mAh. These are scheduled improvements and will enhance the overall experience, but are not designed to address any issues that may be occurring with individual products.
Lumia owners let us know if this solves your battery issue in the comments please.