Tomoaki said the entire design of the Vaio P was based around the keyboard, which is roughly 90% the size of the VAIO TT keyboard. Tomoaki called this the smallest usable keyboard possible, and the rest of the shape was based around this, including the Vaio P's 120mm depth.
This is what birthed the 1600x768 screen, which apparently packs such a high resolution because it's intended for native 720p playback. ORLY?!. Last time I checked, the Vaio P could barely playback standard video, let alone HD. A larger screen was actually planned too, but those pesky Wi-Fi, 3G and Bluetooth antennas got in the way.
The top panel of the Vaio P is an aluminium alloy, the middle is plastic and the bottom panel is carbon fibre.
Tomoaki says there are plans to integrate functionality the Vaio P with that of the Playstation and Walkman line of products. He didn't say much beyond that, but I'd guess it'd have to do with media related features.
There are plenty of other details in the interview apparently (translate at your own risk), such as aborted plans to manufacture a line of accessories which, I kid you not, included a leather Vaio P fanny pack, and a white furry wallet. Yikes. [Engadget Chinese via Engadget]