As opposed to the blunt instrument of, say, TV buys, the numbers trend toward the infinite when you are managing thousands of keywords against scores of creative executions in multiple channels (ie Google, Yahoo, FindWhat, etc) across demographic, behavioral, daypart, and other variables. And it will only get more complex in the future. Smaller firms (such as Key Lime) have sprouted up which focus on addressing this issue (and they keep getting bought), but it’s good to see Yahoo also in the game. I imagine Google will need to respond in kind.
By the way, if anyone has experience using this or similar tools to manage a lot of complexity, and has an extraordinary story to tell of how your marketing plans/return/approach shifted due to them, I’d like to talk to you for my book. jbat at battellemedia dot com, thanks!