Search History

I have recently noticed that more sites and search engines (notably, Bing) are exposing Recent Searches - that is, the most recent keyword phrases used are presented on Results pages.  It would seem to me that a best practice should be that users should have the ability to clear the history, or opt-out of having that information saved and presented by default.

Is there a general consensus out there about this?  Thoughts?

Thanks!

Lija