Syncing and arranging applications from the App Store – You can purchase and download applications for iPhone and iPod touch from the iTunes Store using iTunes on your Mac or PC or using the App Store1 on iPhone or iPod touch. If you are unable to sync applications, or unable to arrange applications on your iPhone or iPod touch screen, please verify that you have followed the steps below. For additional information about using your iPhone or iPod touch, please see the User’s Guide available from apple.com/support/manuals. For additional information about the App Store and applications, please see the App Store FAQ.

http://support.apple.com/kb/HT1977