Coldplay frontman Chris Martin debuted a new song at an Apple product launch in San Francisco today (September 1).

The singer joked “this could be the only time you hear it” as he introduced the track, entitled ‘Wedding Bells’.

Martin also performed ‘Viva La Vida’ and ‘Yellow’, while a video by Lady Gaga was also aired.

The convention was held to mark the launch of Apple’s new range of iPods.

The company has completely refreshed its line of iPods, including a new Nano which features a touch screen. The new iPod Touch also boasts the company' Facetime chat interface.

CEO Steve Jobs also introduced a new version of the much maligned Apple TV, as well as an updated to iTunes.

The new edition of the music store features Ping, a music-based social network.

(by Jason Gregory)