Here are the instructions on how to do it. I guess the concern may be "is it legal"? The site says that "Creating a legitimate, portable Adobe Photoshop & ImageReady CS2 is entirely possible!" They reduce the size of Photoshop to a mire 26MB by removing approximately 212 MB of unneeded materials!

Has anyone done it? I've heard that someone did this and it actually worked on a Linux machine!

http://portableapps.com/node/1426