good question.
Around December I had during my search for a miner for my mining station that i build, I discovered guiminer.
I work for a while with portable applications on my usb stick for home and work and I thought, would not it be nice if I try to make guiminer portable for a usb.
It is not so difficult, the launcher moves poclbm.ini to your usb stick after you have closed GUIminer.
poclbm.ini is normaly placed in: %APPDATA%\Roaming\poclbm\ (on Windows 7 this path translates to C:\Users\Administrator\AppData\Roaming\poclbm)
When you start the launcher, the launcher checks if poclbm.ini exists in the installation directory on your usb, if it exists, the launcher Creates a folder in the appdata > roaming directory and moves the ini file to the folder, then it starts GUIminer.exe
When you close GUIminer, the launcher moves the file to your USB stick and remove the folder, so you do not have to worry that something is left on your PC.
And the advantage is that you no longer have to type in your data when you work on multiple PC`s
