SAN DIEGO—Yahoo! Mobile has launched a $100 million ad campaign aimed at addressing the mobile market – and it means business.

That was the word from David Ko, senior vice president of Yahoo! Mobile, whose job is to make sure that Yahoo's 500 million monthly Web visitors also visit the site via their mobile handsets.

And while the company, known for its Web-based search, e-mail and news portal, has been relatively aggressive in its mobile strategy recently, Ko said during a keynote Wednesday that the company still doesn't see mobile taking over the PC market. Rather, the mobile portion will complement the PC environment, he said.

Ko noted some impressive stats, wherein Yahoo is quickly approaching ubiquity. For instance, total mobile Internet users' compound annual growth rate (CAGR) from June of 2007 to June of 2009 is 45 percent overall. Yahoo's mobile Internet users' CAGR for that same period is 54 percent. Carriers and OEMs listen to stats like that.

Ko said that Yahoo Mobile already enjoys more than 100 partnerships across the mobile ecosystem, but adding to that list is a key aspect of Yahoo's mobile strategy going forward. To sweeten the deal for carriers, Yahoo is working to develop more applications, which it hopes to leverage in attracting more partners. Most recently, the company added Flickr, Yahoo Fantasy Football and Yahoo Finance to its app portfolio.

After a quick demo of the Yahoo mobile app for the iPhone, Ko launched into the issue of monetization, highlighting new ways that advertisers are able to reach the consumer from within the app.

Ko was optimistic that mobile has a lot to offer in the way of advertising. "Leading brands are coming to mobile, and they are no longer just testing the water," Ko said, citing new technologies, such as expandable in-app ads, that will make the medium more intuitive.

While rivals Google and Microsoft have a lot of irons in the mobile fire (re: Android, WinMo), Ko stressed that Yahoo! will not be developing a handset or a platform anytime soon. Rather, the company will continue to focus on what it does best and offer that to OEMs and carriers.