Advertisers using MSN's paid search program, adCenter, now can have their pay-per-click ads targeted to consumers based on their search behavior. MSN is claims to be able to identify likely purchasers based on monitoring users of MSN search.

MSN will be looking at user search history and site visits to determine which of 18 categories the user fits into. Some categories include mobile users, gamers, parents, travel and auto. The advertiser will then have their ad targeted to the appropriate user.

It's an interesting feature aimed at grabbing market share from Google's AdWords and Yahoo Search Marketing. Other MSN adCenter capabilities include targeting by daypart, demographic targeting and geographic targeting.