The search marketing software system, known by its code name "Panama," has been available since October to existing Yahoo customers, and this week is being made available to new advertisers who sign up for a Yahoo advertising account.

Yahoo is making a staged transition before it fully switches on the advertising system in the United States during the first quarter of 2007, giving existing customers time to adapt the new system to their own online ad buying plans.

Yahoo is counting on its upgraded system to help the Sunnyvale, Calif.-based company close the advertising effectiveness gap with rival Google, even as Microsoft gears up to offer its own ad system.

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