A patent that was filed earlier this year by Namco Bandai reveals that the company is developing an inflatable drum controller for the Wii. While the patent doesn't state what game it is for, it will presumably be for their Taiko no Tatsujin series (known as Taiko Drum Master in North America).

A Wii game in the series was released in Japan late last year, so it is possible that Namco Bandai is looking for cheaper controller alternative rather than creating a plastic drum peripheral that connects to the Wii Remote.

According to the pictures in the patent, the Wii Remote is inserted into a compartment in the drum controller, which is accessed by unzipping a section of the peripheral.

Rather than registering a button press like Namco's existing drum controller, the inflatable peripheral is dependent on the Wii Remote's accelerometer to provide input. Tapping the face of the peripheral registers vibration on the Y-axis, and tapping the side of the peripheral will measures vibration on the X-axis.