How to do a "fresh" install of iOS5 once it's out? I have the feeling that my iPhone 4 is getting a bit slower and unresponsive recently (yes, I have closed all apps and turned off/on the device). So I wonder if a clean install (just like reformatting the hard drive of a PC and reinstall the operating system) would help. I thought that the upcoming iOS5 release might be a good opportunity for that. Anyone knows how to do that? Thanks!