Yahoo up and said the other day that starting next month it will anonymize any personal user data stemming from searches, page views, ad views, page clicks and ad clicks in 90 days - a broader policy than anybody else's got although how effective the scrubbing will be is unclear.

Any data held any longer, it said, would only be for reasons of fraud or system security and then any personally identifying marks will be effectively shredded in six months.

Legal obligations, however, may require data be held longer, it added, without explaining how extensive those legal obligations may be.

Yahoo, which said it will take until mid-2010 to enforce the new policy across all its services, had been keeping data for 13 months since a year ago July.

The data is used to personalize content and advertising pitches. Yahoo's motives in changing its policy are supposed to be differentiation and trust. Of course the industry is under increasing pressure from the privacy police.

Last week Microsoft told the Article 29 Working Group, the European Commission's advisory body on privacy, that it would cut the time it keeps web search records to six months if Google and Yahoo would agree to do the same thing, but Google and Yahoo said they wouldn't, according to the New York Times.

Microsoft currently keeps records for 18 months and Google was pressured by regulators to change its privacy policy on IP addresses from 18 to nine months in September.