As I completed my daily roundup of the mobile blogosphere, I noticed a post on Russell Beattie's Weblog about AdMob. Beattie sent out mad props to AdMob for hitting a new record: over five billion mobile ad impressions served. How on earth did AdMob do it?When AdMob launched almost two years ago, I gave them a snowball's chance in Hades. "A mobile ad network? Won't Google just kill them in a year?"

Well, obviously Google didn't kill AdMob. In fact, AdMob seemed to ride Google's push into the mobile ad market with stride. As Google and Yahoo moved into mobile advertising -- and thus legitimized the market -- AdMob was able to stay nimble and ahead of the game. AdMob profited while Google and Yahoo waited and then they eventually launched "trial" programs.

In fact, Google just started testing a mobile version of AdSense in the U.S. last month. By that time AdMob was closing in on its five billionth mobile ad.

Advertisers have been eager to experiment with the third screen and AdMob successfully translated this desire into business success.

Despite this, I still have to question AdMob's success. Is this a sign that AdMob has a killer business offering or that Google and Yahoo are too big and too slow to innovate?

I suspect it's a combination of both. I give credit where credit is due. AdMob delivered. But, I suspect they know deep in the back of their minds that they should have lost already.

I have recently questioned Google's moves in mobile. While the search giant has launched lots of programs, they haven't really built what looks to me to be a profitable business yet. If anyone should be serving five billion mobile ads, its Google. But they aren't.

In May, I posited that Google was starting to look like a slow, giant tech company that couldn't keep up with the times. AdMob's success, in my estimation, is another sign that Google is fast becoming the new Microsoft.

What do you think? Why hasn't Google conquered the mobile ad market? Or is it only a matter of time until they do?