One of the things I have noticed about using the Google Nexus One for more stuff is how awful the battery life is! I can barely get it to last the day, especially if I am using applications. As a phone and a portable wifi hotspot, it seems to be okay, but as soon as I start using Twitter or Foursquare then this seems to kill the battery life.
Yes if I turn off wifi, 3G and GPS then the phone battery does last a fair bit of time, but if I do that I might as well get a cheap Nokia phone which is just a phone!
My iPhone 3GS to be honest also has a pretty poor battery and as it gets close to its second birthday, the battery life appears to be getting worse! What is different though with the 3GS is that I have an external case which includes a battery, so I can usually ensure (even with heavy usage) that the 3GS lasts all day.
However the Nexus One has trouble doing even that!
My solution would be to buy a battery case as I have for my iPhone, but buying accessories for the Nexus One is not easy. Another option would be a spare battery, and I have considered that. I use to do that with an older phone I had a few years back.
My current solution is to carry the charger with me and I also have a car charger in the car too. As the Nexus One has a mini-USB port that does make life a little easier.