There’s a reason that Yahoo! has hired Marissa Mayer away from Google to be their new CEO: she has a keen understanding of product management for the web. Watch this interview for some great insights about human-centered design and development, learned from years of managing web products at Google.
Yahoo! also has some great web applications and tools, but Yahoo! has not been particularly agile with their innovation while the markets that they’re in have swiftly evolved. Mayer should be a wise choice for helping Yahoo! get to a more iterative and responsive place with their web products.