DemoApp is resident at default inside the iPhone IIANM.

To the OP, install Poof. Make sure the version number is the latest. Also heed the warning about taking out all app icons outside of your created Categories, and take out the apps you have hidden before, before you uninstall Categories and Poof.

I'm currently using both the MacOSX theme from iSpazio and Vista Perfection, which requires both Categories and Poof. I basically hide the apps I dont want, which is incidentally, one of them is the DemoApp, the other called FieldTest, and the other one is Contact(named MobileAddressBook).