Mono MICROPHONE ON NIKON D3100?

Another question.
I ordered my NIKON D3100. I found out its mic is Mono? What does that mean? And can't we attach a better mic with it?

The Nikon D3100 (being an entry-level camera) records audio in Mono ONLY (no stereo). This is from a review of the D3100… "the built-in internal microphone captures mono audio only, and there's no facility to connect an external unit. You can choose to turn sound off during recording, but beyond that you have no control over it at all (there's no recording volume control or wind-cut option)."
http://www.dpreview.com/...page15.asp

That means it records a single (monoaural) audio track instead of a left and right one (stereo); it mixes all sounds together instead of recording sounds to the left and right separately.