Looks like they're also teasing other Taito classics yet to come for the iPhone, judging from the collage image (shown here). Based on the other two teaser images, though, we can probably expect Bub and Bob to make their way to the App Store before Chack'n Pop.
For further evidence, observe the sketch of Bub taunting "Guess Who's Coming Next!" and a painfully adorable image of Bub (or is that Bob?) snuggling an apple to the line "Together at Last..."
Go check it out if you can stand the cute.