According to the BBC News online:
Search engines should delete personal data held about their users within six months, a European Commission advisory body on data protection has said.
The recommendation is likely to be accepted by the European Commission and could lead to a clash with search giants like Google, Yahoo and MSN.
Google and Yahoo anonymise user data after 18 months, while MSN does the same after 13 months.
The report from the Article 29 Data Protection Working Party doesn’t seem to be available online yet. As usual, however, the BBC story will give you a good overview of the report if you’re interested.