According to that source, there is only 1 un-aired episode(that being part 2 of the two-parter). This is contrary to Variety's information (which says there are 3 un-aired episodes plus the original pilot). If you click on episode 7 (titled "The Sea") there is some more info. It says that Frank Spotnitz is the one who "axed" Nightstalker on or about 11/13/05 and that the decision was made the next day not to air Part 2. So...I'm not really sure which source is right (not planning on losing sleep over it, either). spirk4life is probably correct in figuring that any un-aired episodes would appear on a Nightstalker compilation DVD. I guess we'll all have to wait till that happens. Whenever.
addendum: I think I mis-interpreted that info over there. Frank Spotnitz is an ABC writer and
he, apparently, notified the news media about Nightstalker's cancellation (on or about 11/13).
At least, that's how I'm (now) interpreting that information over there.