I want to run a content script on an iframe with a chrome-extension:// URL. I added a line to my manifest.json that I copied out of the documentation http://code.google.com/
I'm having the exact same problem, look at the API http://code.google.com/chrome/extensions/match_patterns.html it says clearly that they accept chrome-extension://*/* yet they don't.
They need to update the API so as not to confuse people.