While I'm not going to say that 1930mAh battery is indeed a 1930mAh, in the same packaging as a standard 13xxmAh battery that comes with the N900, it's all about battery technology.

For example, look at these batteries:

http://www.odysseybatteries.com/


These are the same sized batteries as your "regular" car battery, but provide up to three times the Amperage of standard batteries. I guess what I'm saying is, don't judge a battery by it's cover, as it were.