If you own an iPhone with firmware 3.01 and you develop with XCode you have to run this command from terminal to let the XCode compiler to compile for your version:
ln -s /Developer/Platforms/iPhoneOS.platform/DeviceSupport/3.0\ //continues next line \(7A341\) /Developer/Platforms/iPhoneOS.platform/DeviceSupport/3.0.1
