TechCentralStation has an article on developments in the world of search engine advertising and the ongoing dance among Google, Yahoo, and Microsoft.

Author Jay Currie notes:

Google's website advertising program, Adsense, is about to have some fairly hefty competition. Yahoo is testing a "long tail" ad words scheme.

Markets thrive on competition and Google's first mover domination of the adwords market has been inviting a serious challenge for some time. A billion dollars a quarter is enough money to tempt new entrants.