I saw this Craigslist ad, and Im completely unfamiliar with what the heck this guy is talking about:
http://springfield.craigslist.org/pts/514648562.html

Can someone inform me?

I believe that was actually an aftermarket kit, not a factory thing.
After all, that supercharger doesn't look like anything GM would be using. GM would have a snout specifically cast for the application. That one is the one they use on their aftermarket */Cs. It can be cut and machined for whatever specific length the customer needs. The ones they produce for factory applications have one-piece cast snouts with ribbing along the shaft, like ours.

I'm thinking thats aftermarket.

Thats a kit that they don't make anymore. I've seen it refered to a couple times in the past on 60*v6 boards.

I've seen kits available that instead of using an Eaton M-series, a centrifigal supercharger was used.

The other car in this vid:



Is supercharged. His license plate reads "L67 GA"

Not stock of course.

(even though they don't look like any Bonnie wheels I've ever seen)

they where not refurring to the one in the pic.

these where a GM performance kit for a VERY short time, I know someone that had one. I beleave there where less then 10 produced/sold