Sony's Most Impressive Demos At E3 Used Two Controllers, But Apparently Sony Have Things Planned For One Device.

At E3, much of Sony's presentation focused on the use of two motion controllers. However, Yoshida reckons the barrier for entry has to be "as low as possible".
[quote]
"The ultimate goal or wish for us is if you have two controllers, like we demoed at E3, we can do something really amazing. It's like putting your arms into the TV, like a gaming space, and you have total control of the 3D space in front of you," Yoshida said.

"But because of cost-of-goods and, you know, people have to have the PlayStation Eye camera as well, we are approaching the launch by making sure that all games that we create can be played with one controller and the camera. We will also introduce options for if you happen to have more than one controller available. Experiences will be enhanced if you purchase a second."</blockquote>

At E3 Sony claimed that up to four controllers could be detected by the Playstation Eye. Yoshida claimed that, "[The development has] been an iterative process that we are still continuing so every version gets better and better and has some features added or removed. We are still continuing that process."

When asked whether Sony were closing in on the final design, Yoshida responded:
[quote]
"Yeah I think so. Ha ha. We have to finish sooner than later."</blockquote>

You can read the full interview here.