Here's some double news for you. Vietnamese site Tinhte, who has a pretty good track record of verified Apple leaks, is back at it. This time, they are demoing on video what they claim to be a test version of the white iPhone 4 running a mystery iOS.
While it's hard to tell whether this iOS version is legit or not, I can't imagine it being a jailbreak tweak. I think if it was, we would have figured it out by now...