Entering a Hex Wifi Key on an iPhone or iPod Touch

For anyone else having to use a hex string to access their encrypted wifi network over an iPhone or iPod Touch: put a dollar sign in front of the string. Instead of, say 2DBA7C, enter $2DBA7C. It looks like Apple used to let you choose between a passphrase or a hex key in version 1 of the software, but has since removed that option.