: So I've noticed that ever since I installed Mac OSX 10.5 (Leopard) that Apple
: has officially discontinued Classic support. This means Anvil/Forge are
: inoperable witht eh latest OS. What are people using to edit maps with now
: - or are they?
They're using Tiger. :)
More helpfully, there's Pfhorge, which is pretty complete but not very Forge-like. There's Forgery, which is considerably less complete (doesn't even save to the Marathon map format :( ) but has an OS X binary ready. Finally, there's Smithy, which is both a Forge clone and complete up to VISUAL MODE and a few unimplemented texturing features but has to be compiled from source, an arduous task since it's written in OCaml and GTK+ (which in turn means it has to be run under X11, at best like Gimp.app).
I don't know if Basilisk II can be made to work on OS X, but that's an emulator for pre-OS 9 (I think) machines, and so if you had a Mac ROM image and a disk image (or a pre-OS 9 installation disk), you could emulate Forge and Anvil. Again, this is assuming that it works at all.
Personally, if you're man enough, you should attempt Smithy. If you aren't man enough, you should attempt Basilisk and, failing that, Pfhorge.