Is Amazon About to Change UIs?

The last few days I found that Amazon has been serving me a different UI than on other computers. Click on the screenshots for a larger view.

Old UI:
Screenshot of Amazon's old UI

New UI:
Screenshot of Amazon's new UI

There’s a clear shift here away from category-based navigation and towards search as the primary tool to find products. It would be more interesting if Amazon began serving up different UIs based on user profiles, but more than likely they’re testing this particular UI out before a full release. They must have a ton of data on user behavior from all of their UI iterations, but I doubt they would pursue such a shift due to the added cost of maintaining multiple UIs.