Apple and Google used to be close. Google's CEO Eric Schmidt was even a member of Apple's board for three years.

You know, I've got the privilege of joining the board, and there is a lot of relationships between the boards. And I thought, you know, if we just sort of merged the companies,we can call them AppleGoo.

A lot of love there from Schmidt on stage of the Iphone Launch in 2007.Why? Because every phone Apple sells includes Google maps, and Youtube,and the Iphone's default search engine is Google. But since then, competition has been building. In November of that year, Google said it was coorporating with alliance of hardware companies to develop Android, a software platform for mobile phones to directly challenge the Iphone. HTC, Motorola and Samsung have all released their own Android phones. And earlier this month Google released a phone under its own brand , the Nexus one. Now it also released a web browser to compete with Apple Safari, and announced plans for operating system called Chrome OS. Apple said Google's emergence as a competitor was one reason why Schmidt left the board of Apple last August. Apple's move has been a little bit more secretive. Reports say it bought a mapping company called PlaceBase in July. Business Week reported last week that Apple is in talk to the old rival Microsoft to make Bing, the default search engine on the Iphone. On search is what Google is most famous for, but it makes most of its money from advertising.Now Google is turning its attention to Mobile advertising by Admob in November.Then why the sudden interest in Mobile ads?The answer is on AdMob homepage, Apple's Iphone. AdMob's CEO said the Iphone led to a landside of massive improvement in Mobile advertising , so it's not surprising to learn that earlier this month , Apple bought a mobile advertising firm of its own, Quatro Wireless. And selling mobile ads it might not be as exciting as selling music or phones, but it could be Apple's boldest move yet and another shot at its one-time ally Google.

Kristie Lu Stout,CNN HongKong.