It appears all new controllers will be getting this accessory bundled with it however Nintendo are allowing existing owners to claim free ones for their existing Wii's.
Details: http://wii.nintendo.co.uk/22686.html
Claim: http://wii.nintendo.co.uk/22690.html
Note: Max of 4 and you'll need your Wii serial number.
Details: http://wii.nintendo.co.uk/22686.html
Claim: http://wii.nintendo.co.uk/22690.html
Note: Max of 4 and you'll need your Wii serial number.