I recently found an application called CorkScrew Photoshop CS5 which I will not link to (Google it). It is really just someone's wrap of Photoshop CS5 running wine in which makes it incredibly easy to install Photoshop for linux. Once I downloaded it all I had to do was chmod +x the InstallerPhotoshopCS5 file (make it executable) then run it to install Photoshop CS5 (and might I say, it was FAST). You may be confused by not seeing it anywhere (except maybe your desktop if you have one), but if you have trouble launching the launchers it pre-made for you on your desktop (gives you errors) please follow the guide below on how to make a simple executable to run it from your favorite application launcher.

To solve this I made my own executable to launch it from my application launcher in wmii. Simply go to a terminal and type in 'sudo nano /usr/bin/photoshop' and type in your password. In that file paste in

!/bin/bash

wine .wine/wineprefixes/PhotoshopCS5/drive_c/Program\ Files/Adobe/Adobe\ Photoshop\ CS5/Photoshop.exe

Hit cntl+o, hit enter, then hit cntl+x. Once back to the normal terminal prompt type in 'sudo chmod +x /usr/bin/photoshop'. Now refresh your application list however you do that (in wmii I hit ModKey+A then run rehash, then I can launch it from the ModKey+P).
Below is a screenshot of me making the hero for this blog post on Photoshop CS5 inside Ubuntu Linux (running wmii).

Happy Photoshopping under Linux!