Despite many false alarms in previous years, mobile advertising is finally taking off this year thanks to a confluence of factors, says the Kelsey Group.

In a recent article on ClickZ, Matt Booth (VP and program director of The Kelsey Group’s Interactive Local Media practice) said, In almost every mobile forecast, it’s always been next year will be big. This time, there are several factors coming together that should drive mobile ad adoption, and start pushing the market.

The Kelsey Group’s U.S. Mobile Advertising Forecast claims that the U.S. mobile ad market will grow from $33.2 million in 2007 to $1.4 billion in 2012, a compound annual growth rate (CAGR) of 112 percent.

Other analysts have predicted the mobile ad market will grow to anywhere from $1.5 billion to $2.9 billion in 2011. The end result of course depends on the definitions and assumptions being used, but overall, every forecast calls for huge growth in the mobile ad space.

One of the biggest drivers of the mobile market will be Google, which needs to find another outlet for its text ads. With the rapid growth of search slowing due to the sheer size of the market, Google will need to look elsewhere to keep investors happy. Mobile ads could be a natural extension of that, since the existing text ad format would also work for mobile, Booth added.

Microsoft is also expected to make a big push into mobile advertising, in an attempt to beat Google to the punch. Microsoft has been investing heavily in mobile, including the acquisition of TellMe in March, and hopes to extend its adCenter platform to mobile ads as well

Yahoo has likewise made some investments in mobile, and has a very popular product with its OneSearch application, as well as a strong subscriber base to market that product toward, but their mobile efforts lack focus, according to Booth.