Running Apple Macintosh programs on Linux now a possibility. And a listing of other emulators on Linux.
The new Darling project is a loader for Linux that allows a Linux distribution to run unmodified Macintosh OSX binaries on a Linux system. The GNU Libc and other parts of a Linux distribution need to be patched to allows this to work; but this would mean that a user could purchase the Macintosh OSX version of Photoshop and run it on their Linux machine; that would be better than running Photoshop with Wine. The GIMP in version 2.8 as well as other Software like Krita already supply a good image editing capability to the Linux platform, but if you could run Adobe Photoshop and run the countless plugins available for that image editing suite as well as the video editing software available for a Mac then that would make Linux an even better platform for the desktop. Since this is an emulation layer for Linux it would work like Wine; even though Wine is not an emulator; it is the same premise. Allowing software released for Apple Macintosh computers to be run on Linux. It might be quite a while before this is capable of running Adobe Photoshop; but this is an interesting project nonetheless.
Linux has had many applications for running programs written for other operating systems on the Linux platform. There was Win4Lin, a package that allowed you to run Windows programs on Linux. This was a proprietary solution and supports Windows Millenium Edition and Windows `98 Second Edition. So it is very old indeed. Then there is the Boschs emulator; which is more up to date and supports the emulation of various operating systems on a Linux platform. This could be useful for running Windows XP in a window on your Linux desktop. If you are running Fedora; then you have the Xen virtualization system that also may be used to run another operating system in a window on your Fedora Core desktop. I have used this once and it was very easy to use; I was running Fedora Core 14 and I had Fedora Core 3 running in the Xen window. This worked very well indeed. This is integrated into the Fedora Core distribution with a specific Xen enabled kernel and other packages that go together to make it work. But it is not very hard to install or use.
There is also Virtualbox; this is rather similar to Xen; but simpler to install; the only hassle if you have a custom kernel build is the compilation of the kernel modules. This solution is a quick and effective way to run another operating system on your Linux desktop. You can install Windows 7 in Virtualbox with the guest additions and it is a very fast and usable operating system if you do not want to install Windows natively. I have used this quite a lot on Linux. Finally; there is Dosbox. This is an emulator that runs the FreeDOS operating system and allows you to run very old DOS software and games like Blood and Doom. This is heaps of fun to use on Linux; you can even run Windows 3.11 for workgroups if you really enjoy suffering. DOSEMU is another DOS emulator that may be installed on Linux and used to run old software. This is very useful; you do not need to mount the /home folder first like you do with DOSbox, just load DOSEMU and you are ready to go. You can play some games with DOSEMU as well.