I recently bought a MacBook Air with Mountain Lion & have been using my Samsung SCX-4200 multifunction via my network on my Snow Leopard Mini.
Today I wanted to quickly print without booting the Mini & found the SCX-4200 not known by ML...
Tonight I downloaded the Lion drivers from the Samsung site, they appeared to install fine but still no SCX-4200 in the Add Printer box... eventually decided to try the built-in drivers for the slightly newer model. The Samsung SCX-4300.
The install threw up an error and asked to repair something like a "fine print" option so I selected off for that. Now printing & scanning ok on Mountain Lion.
Note that using the wrong drivers can be risky so if in doubt, don't.
hmmm now I see another post with the same advice, odd it didn't come up earlier when searching. A pain I can't delete this one!