"Do note that installing the iOS 7 update through OTA requires over 3GB of space initially, despite the download being much smaller than that. That is so the update can unpack and install – it does not take up that space when completed. Basically that means you will need at least 3GB of space available on your iPad, iPhone, or iPod touch before it will install.
You can also install the update through iTunes, though you will need to get iTunes 11.1 first so that you can sync the device afterwards. We will be posting direct download links to the IPSW firmware files shortly.
If you’re waiting until later to perform the update, don’t forget to follow our thorough preparation guide. At the very least, back up before beginning your 7.0 update!"
osx daily