I don't understand why you'd have an app on your phone that you want hidden. If you don't want people getting into your phone you can put a passcode on it. Also, the new iOS4 software will enable you to put apps into folders, thus making them kind of invisible. but once you tap on the folder you can see all of the apps that are in the folder. Technically, if you want a open background to your phone you can take all of your apps and put them into one folder. That is the best you can do. I hope this helps you

Here's a link to what the new software will look like.
http://www.apple.com/ipodtouch/ios4-soft…