In the Windows world, moving an application can be a real pain. Thanks to reliance on the registry, it can sometimes be easier to reinstall an application than to move it from one internal drive to another. Of course, Mac users have no problem with this concept - even before OS X. Want an app in a different location? Just drag-and-drop it where you want it. Of course, on a corporate network, you may be restricted to where you run an app from. However, this run-from-anywhere mentality extends to removable media, including USB flash ("thumb") drives.