The German web site Spiegel has an interview with Marissa Mayer. If you don't know any German, Google Blogoscoped has published the key points of the interview in English.

Some key quotes from Google Blogoscoped:

Marissa says Google is spending a great deal of their time battling spammy link farms. She says naturally, Google’s algorithms analyze whether or not all links are from the same site. She also admits that there’s no defense against Googlebombing, as the linking network can be very widespread. “It’s enormously difficult to differentiate between an act of manipulation and a relevant result; for example, when a company introduced a new product with a fantasy name.”

And then

Asked about an Ask Jeeves feature which allows you to narrow a search by clustered topics, Marissa answers: “Do you want to know what I really think of this? It’s interesting, but not really useful.” She adds that the majority of users don’t really want to narrow their search, they want an instant answer, and that for those users Google gives the fastest results.

You can read the whole thing in English here.