Jnes on Mac???

Doesn't the Mac have a windows "emulator" of some sorts? I'm not sure, mind you, because I don't use mac's (urgh!), I've just heard some things. Perhaps if you can use this "windows" emulator you can get it to work? Other than that, there's no mac version in the downloads, so I doubt that it's available.
- Modem

No, at least not yet. But there are plenty of other NES emulators for Mac:

http://www.zophar.net/mac/nes.html