This is a bit more than A/B testing fonts, colors, and so on, though. They have almost completely replicated the look of Google, except with a Yahoo logo. It's

This is a bit more than A/B testing fonts, colors, and so on, though. They have almost completely replicated the look of Google, except with a Yahoo logo. It's an interesting catch-up technique. I assume they are not looking to copy the UI in the long-term, but are looking to establish a baseline.