Lots of hand wringing among agencies about Ad Planner. The good news, however, is that the availability of free data will dramatically increase interest in online advertising and media planning, the same way that Google Analytics dramatically increased interest in Web site traffic statistics. Did the release of the free Google Analytics kill off the established vendors like Omniture, Webtrends, CoreMetrics et al? Not yet. In fact, it provided a much-needed split in the industry between do-it-yourselfers and serious analytics consultants using enterprise tools.

Ad Planner will do the same for online advertising. Small and medium clients and agencies will increase their Internet ad buys due to the comfort of having real data about thousand and thousands of sites. And the big guys will continue using the enterprise solutions.

As far as where the data is gathered from, I wouldn’t jump to conclusions about it coming from GA. There are plenty other data aggregating options out there such as running demographic information through IP addresses and determining demographics per region – quite a bit of data can be gathered if you know the region of the user.

I wasn’t really WOWed by Ad Planner in its current form – there’s nothing there that Quantcast doesn’t already provide though it’s pretty clear that the two are using different data sources.