Mac OS X fonts licensing?

Yes.

Let me caveat what Kappy said a bit since it depends on what you mean by "used within a commercial application". You can use the font to create documents that will be printed and distribute such printed copies without restriction. But if you want to distribute the actual font file with an software application to other people, that may well take a license from Apple. If that's what you mean, you'll want to contact Apple Software Licensing:

http://developer.apple.com/support/mac/licensing/

Regards.

Dave,

Thank you for the clarification. Very helpful.

No problem, Kap. You probably understood the issue correctly, but I wanted to be sure.

Cheers.

I do but honestly didn't even think about it. Sometimes I get stupid. CRS disease, you know.

Since Apple fonts are all, to the best of my knowledge, copyrighted (at least by someone if not by Apple), I'd suggest you contact Apple Licensing (or their copyright office) and ask. That way you have the accurate information for your specific use.

You might also look around the web for a font that would be in the public domain that you could use without needing a license. I don't know if there's one that would be exactly what you need, but it might be worth hunting around a bit.

Regards.