There is a listing here on Amazon for a Canon 1Ds Mark IV underwater housing that ships in 2-3 weeks.
Of course the product shown is not branded as the 1Ds Mark IV housing, but rather a 1Ds Mark III housing. While it could be a placeholder for a soon-to-be-announced product that slipped out, it may be more likely that this an attempt for the third-party seller to grab some attention.
Aquatica’s own website shows no listing for a Canon 1Ds Mark IV underwater housing as of the time of this post.
[Thanks for the tip Matt.]
If you see any other suspicious leaks or rumors, feel free to drop a line via the contact form.