The new form of usability?

I was looking at the style switcher contest over at Smashing Magazine when I had a revelation... What if you used this idea as a way to usability test your product? Here is the concept:

• create a highly customizable version of your site
• break your site into discrete elements and make each element editable
• let users of your product make changes to each element
• record the changes that each user makes
• aggregate your observations to find which layouts people preffer
• make those layouts the "default" choices with the option to change to the OTHER most popular

I'm thinking in terms of websites such as amazon.com. Allow the visitors to customize what they are seeing on the page and where that is placed. Especially with a large site you will see in a matter of hours (maybe days) what configurations are the most popular and can start to make changes to your default to better suit the needs of your users. Is it just me or does this seem obvious? Anyone know people who are doing this?