People Search - is this real?

People Search is now a days the hot keywords in many of the search engines. Is this really real stuff that People are looking for this kind of people search on the search engines? And does people search give you the genuine results?

Google and Yahoo are paying highly for the this key word "people search". So, now is the information that we add on social networking site really safe or it is vulnerable to these people searches which extracts info of person and store for this kind of people search.