Peter Fleischer, global privacy counsel for Google, wrote an opinion piece in the Financial Times: Google's search policy puts the user in charge.
He points out how personalization can help make a better search for the user. Using his example of Paris, you can see the disparate results in the Google [Google Results]. I find is useful to run the same search on Clusty.com, where the search results are organized by topic [Clusty Results]. Are you searching for Paris Hilton or Paris France?
The question that arises is whether personalized search belongs should be used in the enterprise?
Google's method of personalizing the search is based on prior searches that you run (once you have elected to have them track your searches). Presumably, they could also customize the search based on user profile information that you provide. For example, if I search for Toyota, the search results should have more websites from Boston (where I am) than Kansas.
Of course personalized search on the internet raises privacy concerns. And since many user profiles are fictitious, leveraging the user profile may be of less value than tracking search results.
The same concerns are not as true for a search inside the enterprise. User profile information is generally detailed and verified. However the search history is generally much more scarce. (I find users much prefer to browse on the intranet and search on the internet).
A typical user would not be as shocked by the intranet recognizing who they were and displaying information personalized for them. I actually think it is good intranet design to have some of the content, especially the starting page, personalized for the user.
That personalized content is easy to explain why they may see different content (You are in the Boston office so you see the Boston weather, while someone in the San Diego office sees the San Diego weather).
With the search results personalized, it is harder to explain to a user why they may see one set of results and someone else sees a different set of results.
I prefer the clustering of results around topics over personalization of the search. Putting the extra context around the results makes it easier to focus on what you are looking for. You can then replicate the findings from user to user making it easy to share content across the enterprise.