Very interesting, but you're not exactly correct on one thing: that download was only available starting in June. Before that, if you owned an airport extreme (which has been out for at least two years now), you were out of luck, as the others you link are only for the express.

In the past, if you lost your disc you had to find someone else with an airport extreme and borrow theirs.

Anyway, I'm glad to see they finally got around to putting it up online. I still don't think it should have taken this long.