Bill Slawski at Search Engine Lands posts a great summary of Microsoft Researcher Susan Dumais' Big Thinker talk at Yahoo Research.
A low res video of Susan's talk is available. All of the talk is worthwhile if you can tolerate the quality of the video, but don't miss the part starting at 41:50 where Susan talks about her work on personalized search.
For more on the work of Susan Dumais and her group at MSR on personalized search, see also my previous posts, "Beyond the commons: Personalized web search" and "Personalized search paper from MSR".
For thoughts on how this and related work at MSR might be used by Microsoft to pound Google over the head, see also my previous post, "Using the desktop to improve search".