Microsoft's Bing blog announced they will reduce the time frame they store search data, from 18 months to only 6 months. This is in response to the European Union's request that search companies reduce the time they store such data. Microsoft Bing is the first major search engine to comply with those demands.
Specifically, we are reducing the amount of time we store IP addresses from searchers to 6 months. Currently we keep that information for 18 months before we delete it. Generally, when Bing receives search data we do a few things: first, we take steps to separate your account information (such as email or phone number) from other information (what the query was, for example). Then, after 18 months we take the additional step of deleting the IP address and any other cross session IDs associated with the query. Under the new policy, we will continue to take all the steps we applied previously – but now we will remove the IP address completely at 6 months, instead of 18 months. We think this gives us the right balance between making search better for consumers (we use the data to improve the service we offer) and providing greater protection for the privacy of our users.
Greg Sterling at Search Engine Land has additional history and insight into this change.
Forum discussion at WebmasterWorld.