Look out comScore, Nielsen, and Hitwise. Anytime a company like Google puts out a product that is functionally rich and does it for free, the companies that sell something similar are going to suffer. This happened when Google Analytics came out, it will happen here.

What will be interesting to watch is how companies that are offering ad spend analytics will adjust to accommodate Google. I am thinking Rubicon Project and AdMeld specifically. It may be that these companies are not affected because they are optimizing spend across a portfolio of ad networks, of which over 300 exist to chose from.

To make your life easier, we’re introducing Google Ad Planner, a research and media planning tool that connects advertisers and publishers. When using Google Ad Planner, simply enter demographics and sites associated with your target audience, and the tool will return information about sites (both on and off the Google content network) that your audience is likely to visit. You can drill down further to get more detail like demographics and related searches for a particular site, or you can get aggregate statistics for the sites you’ve added to your media plan.

[From Inside AdWords: Introducing Google Ad Planner]