If you need any more evidence that mobile advertising is booming, AdMob is getting ready to serve its 100 Billionth ad. The firm notes that this is over 14 times the entire world population (as of 2008), 107 times the distance (in miles) to the sun, and about half to a quarter of the number of stars in the galaxy. Suffice it to say, that’s a lot of mobile advertising. And that’s just from AdMob.

A spokesperson for AdMob tells WebProNews that smartphone shipments worldwide are projected to grow 13% this year. You can expect a lot more mobile advertising to come.

eMarketer estimates that there will be 280.8 million mobile phone subscribers by the end of the  year. comScore says there will be 29 million smartphone users. eMarketer also projects that US mobile advertising spending will reach $760 million in 2009.

"Not that long ago, mobile used to mean simple WAP sites or worse, trying to view a traditional website with a sub-par transcoded experience," says AdMob. "Remember how fun it used to be to squint your eyes to try to read web sites intended for PC viewing as they slowly appeared on your old flip phone?  Mobile websites have come a long way since then and now provide a rich user experience optimized specifically for mobile."

"More and more people are getting smart (with a smartphone) and mobile has become a real medium for advertisers & publishers," Admob says.  "No longer for just early adopters, as smartphones have become mainstream, having a strong presence in the mobile landscape has become essential for both mainstream brands and emerging developers alike."

WebProNews recently interviewed a former Yahoo executive, who is now the Chief Revenue Officer for mobile advertising firm Crisp Wireless. He says we’re going to see nearly all major brands embrace mobile in some fashion this year. According to him, the most successful mobile campaigns recognize what will appeal to consumers while they’re on the go.