Yes, you're coming late to the party: Jobs was long gone by the time the Plus came to market and certainly by the time the SE & Platinum Plus with the revised analogue board hit the streets. There was no love lost at Apple to prevent them from sticking a fan in there and mitigating their repair costs.
Aoresteen, you are quite right and I have two of them, a Kensington System Saver and a much more elegant one that fits flush inside the handle area, but I forget the name, maybe MacCool. There were many others, but those are the two most common I have seen. Larry Pina's book has a whole chapter devoted to doing it yourself as I think Tom Lee's paper does ... And don't forget the Mac Chimney. ;-)