It seems Sony is about to become the latest big name brand to enter the small, low-cost ultraportable market.

A prototype of the laptop, based on the recently announced open-source Via OpenBook reference design, has been spotted at the WiMAX Expo, part of the Computex show in Taipei.

Shown on contract manufacturer Quanta Computer's stand was the small notebook featuring Via's 1.6GHz C7-M processor with Sony listed as the manufacturer.

Specs for the notebook were said to be an 8.9-inch screen, 80GB hard disk, Wi-Fi and Bluetooth. Optional extras include AGPS, WiMax and 3G.

It's being reported that "when the existence of Sony's name on the machine was pointed out to a Quanta executive manning the booth, he quickly closed the properties window and declined to explain why Sony was listed as the manufacturer".

The laptop will begin shipping during the third quarter, Quanta said.