Yet another Apple Patent filing seems to confirm plans to release an iPhone.

Bloomberg News' first revealed a new patent for an enclosure for such a device that would be conductive enough for RF signals.

The new patent seems likely to cover a device that combines a phone with a music player. Its revelation has sparked yet another wave of optimism that the iPhone may debut - perhaps in January 2007.

The patent was filed in August and published by the US Patent Office yesterday. It is focused mainly on the development of a new type of enclusure for such devices, based on ceramic material, Zirconia. Many will already be familiar with Zirconia - it's a material used to create fake jewellery.

"The enclosure includes a structural wall formed from a ceramic material that permits wireless communications therethrough. The wireless communications may for example correspond to RF communications, and further the ceramic material may be radio-transparent thereby allowing RF communications therethrough."

At a later point, the filling remarks: "There is a need for improved enclosures for portable computing devices," the filing explains. "Particularly, enclosures that are more cost effective, smaller, lighter, stronger, and aesthetically more pleasing than current enclosure designs."

Commenting on the news, Roger Kay, president of the market-research firm Endpoint Technologies, told Macworld: "Everyone had already triangulated that this was likely – it makes a lot of sense.

"The only market larger than computers is the phone market. Phone companies have the potential to eat the media player market, so Apple can't leave that base uncovered."