Fading of the URL in Safari 6's Unified Search and URL Field
As mentioned above by dan8394, you can click the omnibar, reactivating the full URI. Unfortunately, there is not an option for changing this in Safari, nor does a hook exist in AppleScript. To the best of my knowledge, the only way this can be changed would be through a Safari extension. However, from what I have found, this is hard-coded into Safari itself and there isn't an option or a flag to change that will affect it. Sorry.

Good luck and happy browsing!