Has the final Mega Man 9 secret been discovered? Probably not, but this is a pretty neat Easter Egg nonetheless. First, observe the following screenshot from Mega Man 9. Take note of the circled area:
Next, check out this screen from the opening of Mega Man 4, which details the origin of the Blue Bomber:
Of course, Seth is away at the San Diego Comic Con at the moment, so it may be just a little bit before we get any clarification. Nonetheless, a good find by new Capcom*Unity member Alexis (via Protodude).
On the other hand, I think that perhaps another newcomer, JohhnyDamage, may be on to something with his theory, just a few posts down from Alexis':
I just read 42 pages, and I think I know the secret.
It's love. It was inside us the entire time during this adventure. I'll take my kudos and any Mega Man/Ghosts and Goblins figures you want to send me for my computer desk.
Somehow, I wouldn't be surprised.