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NICK DOUGLAS — Yahoo starts its "Panama" search ad system today. It could bring Yahoo up to speed with Google, which now makes almost twice as much as Yahoo per search. Here's what you need to know.

What's Panama? Yahoo's ad system, announced last May, formerly due late last year, finally released at 3 p.m. today. Under Panama, search ads should be better targeted, which should increase the number of users who click on them.

What will I notice? If the changeover goes smoothly, users will notice nothing. From then on, though, more of the ads they see should seem worth clicking.

What will Yahoo notice? Hopefully a higher profit per search. Right now, one analyst estimates Yahoo makes about 60% of what Google makes on any given search. That's the main reason why even though Yahoo gets more pageviews, Google makes more money.

What will advertisers notice? More information and control over their ad campaigns, including a "quality index" that shows them how well a given ad is expected to perform.

Will it work? Eleven thousand employees can't be wrong! Yahoo execs say it'll revolutionize the company, but so do engineers with no press to impress.

What do I say at a business party? "Didn't you hear? Yahoo is back. Yep, I'd grab the stock while it's under $30 before Panama kicks up the earnings later this year."