The Post-Google Generation is a TR (Technology Review: MIT's Magazine of Innovation) blog entry updating their excellent article in March 2004 on Search beyond Google (subscribers only). Some interesting points of the original article are:

• It's easy to switch engines, so the competition to be best is intense. Google employs more than 60 PhDs.
  
• There is little infrastructural advantage to perpetuate dominance at Google, but watch out for what Microsoft could do - building search into the operating system, and searching across your hard drive, email, intranet, and the web.
  
• Google uses PageRank.
  
• Teoma uses a page's standing among recognized authorities on a topic.
  
• There is open-source work on search, e.g. Doug Cutter.
  
• About a quarter of users don't find their answer in the first set of links returned. That sounds pretty good to me.