Google is beta testing personalized search.
It's a profile-based approach (not what I would use) and it doesn't appear to be all that effective. But it's an impressive step forward.
Personalized search is inevitable. With only one general relevance rank, it is increasingly difficult to improve search quality because not everyone agrees on how relevant a particular page is to a particular search. At some point, to get further improvements, relevance rank will have to be customized to each person's definition of relevance. When that happens, you have personalized search.