The Nokia N81 8GB-packed music phone is likely to be one of the new multimedia phones introduced by Nokia at its London launch on 29 August.

The Nokia N81 hasn't been officially announced by Nokia yet. But a viral advertising campaign is underway which features what appears to be the N81 with a countdown timer onscreen counting down to 9am on 29 August. That's the time of Nokia's UK press launch (Tech.co.uk will of course be reporting from the launch).

The 29 August launch event, with an evening bash at the Ministry of Sound, has also fuelled speculation that Nokia may be about to announce a music download service to take on Apple's iTunes Store.

The Nokia N81 is rumoured to be an 8GB music phone, the successor to the Nokia N91 music mobile. According to previous reports , the Nokia N81 is expected to be a 3G HSDPA sliderphone featuring a 2-megapixel camera and secondary video call camera.

N-Gage gaming platform

It will feature extensive music player functionality, and is also thought to be one of the first wave of new Symbian S60 smartphones to feature Nokia's new N-Gage gaming platform.

The viral ad involves a moody black screen with moving shapes and swooping coloured spotlights moving around apparently randomly, occasionally forming the shape of a phone.

Information on how to make sense of the ad has been posted by Intomobile.com . By clicking a pause icon in the centre of the screen when the phone shape appears, you get broken images and sound coming onscreen. After dong this several times, eventually a message: "I'll be seeing you in the next episode" is revealed, followed by the countdown timer.