Apple's not really going to release anything based on Linux. Unix yes, Linux no.
You could argue that some of the open source components (Darwin) that make their way to Mac OS X and Server will borrow some stuff from Linux, but that's about it.
Additionally, the bit about WordPerfect being free on Linux, but a commercial purchase on Mac is extremely rare. I don't know of any other application that is in that same situation.
Yes, there is much more free software for Linux, but rarely is it the same brand/product as a Mac or Windows one.
[This message has been edited by scott (edited 08-02-99).]