Grant Paul, aka Chpwn posted a tweet saying “Taller screens like Cydia too. :)” with a screenshot of the Cydia icon running on the iPhone 5. In a second tweet he posted a screenshot of the Cydia homepage on the iPhone 5.
This looks like the real deal since it comes from a respected jailbreak dev. This also means that there is hope for jailbreaking A5X devices on iOS 6 as well. We will keep you updated.