The PDP Headbanger Headset is a product created by Performance Design Products, who are known for creating various accessories for the Wii and other systems. The headset is used for chatting online with games. The headset is not wireless so it has to be plugged into the Wii by a USB cable. Although it's a third-party product, it's licensed by Nintendo.
PDP has confirmed that the device will not work with any previous Wii Speak titles. This is because of an IOS that needs to be on the game disc to allow it to work. Some of the voice chat titles are compatible with the PDP headset, which seems to replace the Wii Speak. For example, The Conduit was compatible with Wii Speak. Conduit 2 is now compatible with PDP headbanger headset, removing Wii Speak functionality.
Currently, there are only 3 games that support the headset: Call of Duty: Black Ops, Conduit 2, and Call of Duty: Modern Warfare 3