That has been discussed before. AFAIK, and experience backs this up, the above applies mostly to laptop batteries, which are stacked batteries (that is, cells not only in parallel but in series too). I'm almost 100% certain that there's no such fuel gauge in the kind of batteries used in the NITs and similar devices, instead there's a simple voltage meter in the device which measures the current voltage and calculates everything else from there.

For the record, my N800 is from January 2007 and the battery metering works exactly as it's always done, and I avoid discharging the battery like the plague (it's happened by accident maybe 4 times).