audience tracking is meant to be improving advertising and your online experience. the idea is that the more we know about you, the better the ads we cand eliver to you.
interestingly enough, this is a technology that is moving much faster than the media buyers and 99% of publishers. the only people taht really seem to have honed in on this are the ad networks at the moment to improve CTR’s and even they often dont carry enough advertising inventory to achieve that.
google is the top tracker (their adsense network) with MSN second (hotmail, msn, IM etc) and so the quantum of data there is interesting – but is it usefull?
from my experience, and as interesting as i think this area is, the data acquisition and data based decision making on ad serving is in its infancy. we still dont have real data matching and geo overlays (i.e. when i can match a loyalty card owner to an ad profile, then i can really start looking at some interesting ad overlays) and we still dont have a media buyer maturity to do this. in fact, this technology dramatically changes teh face of media buying by taling a lot of the guess work out of the process.