Well, "Me too", as they say.

OS X 10.4.9 on a G4 Mac Mini, USB via the spare keyboard port. It also auto-launches iPhoto, recognising the SD cards as if they were a camera, and when you click the Eject symbol in the iPhoto listing, the same thing happens, the unmount and mount again.

Same procedure if you drag to the Trash.

I tried dragging to the Trash and immediately pulling the cable, but with two cards, I think the first was on its way back as the second was on the way out, so I still got a Finder slap on the wrist message saying don't remove media without ejecting it.

The Disk Utility "Unmount" mentioned by U. Fury above does the trick, but if you also click "Eject" in Disk Utility, the cards re-mount.

Tomsk.