If you cannot wait for the release of iOS 7 you can download the OS and install it now on your iPhone, however legally you do have to be a developer.
It is thought that Apple will reveal iOS 7 in early September and the final build for developers is thought to occur around 5th September, with the release to the public being on 10th September. However if you are willing to cough up $99 to become an app developer, you are able to get hold of the beta version 6 and install it.
You can still install it without paying to become a developer by getting hold of the IPSW file with the build code 11a4449d; however we cannot condone this as it would be illegal.
If you do get hold of it one way or another, here is how you install it. If you have already installed a beta build of iOS 7 then you can update it OTA.
Backup Your Device – I always recommend backing up your device (either to iCloud or to your computer) prior to updating major software.
Update iOS and iTunes – Check that you have the latest versions of iOS and iTunes. For iPhone 5 owners, it is iOS 6.1.4; for older iOS devices, it’s 6.1.3. For iTunes, the latest version is 11.0.5.
Download the Build- Download iOS 7 beta 6 IPSW from Apple’s Dev Center for iOS. We at PCMag do not condone downloading unsanctioned/illegal builds of the iOS 7 beta, but of course, they exist.
Connect Your iOS Device to iTunes – Plug in your iOS device to your computer. In iTunes, navigate to the device on the left rail.
Install the File – In iTunes, hold down the alt or option key, and on Windows hold shift while clicking “Restore your iPhone/iPad” with the iOS 7 beta 6 file by.
Some users have reported that non-developers can hold down the option key or shift on Windows, and click the “check for updates” button instead to circumvent the verification process of the UDID (which if you are attempting to install an illegally downloaded copy of the iOS 7 beta, you’d need to do). Please note that I have not personally verified whether this works and don’t condone it. If you do try to go this route, however, you may need to make sure the file name ends in “.ipsw” and strip off any other characters that may follow that file extension.
You’ll see your iOS device reboot, with a progress bar filling in all the while. Be patient, because it can take a few minutes.
When the build is installed and verified, you’ll see a few iOS 7 setup prompts, which you can complete to finalize your upgrade to the new UI.