Don't most mac programs have a windows version as well.
As far as I know, their doesn't exist a macosx API for linux (like Wine).
I've toyed around with PearPC (a mac emulator) but that really wasn't as pleasant as I hoped it to be:
It's a start and absolutely not useless.
I'm still hoping for a Xen or VMware client though.
PS: Most mac(OSX) programs are actually very easy to port.
I just doubt that Aplle will ever be willing to do(or allow) so...