Just unplugged it again. After 4 seconds I checked the status. Maps was responsible for 5% of the battery drain in those 4 seconds. I then opened Advanced Task Killer to see what's running.
Android Live Wallpaper (set to Nexus right now)
News and Weather
Advanced Task Manager
That's it. How could Maps have used any battery? And why is it that other program names never show up in this list of battery usage stats? It's always just like Display and Cell standby and stuff.
After 2m 49s since unplugged:
In the first place, keep in mind that 16% does not represent 16% of your battery; it represents 16% of the battery USED in the 169 seconds since you unplugged your phone. For example (.16 * .001) or so.
But as to your question, I'd bet dollars to doughnuts that your News and Weather app is using maps.