I was on a call with Mobclix in which, among other things, we discussed location targeting and other types of targeting on mobile devices. The fantasy of mobile marketing and advertising is "right ad, right time, right place," also known as 1:1 marketing. That phrase is repeated almost as often as the joke about the last ten years each being the "year of mobile."
What agencies and large advertisers want is reach. They want audiences and targeting but not at the expense of reach. In other words agencies and advertisers need big audiences that cross certain traffic thresholds before they'll pay attention.
But the 1:1 marketing fantasy flies right in the face of those requirements. Same goes for LBS marketing (which ofters targeting but at the expense of reach; if you slice audiences by location they get smaller and smaller). This is a contradiction that is surprisingly not discussed very much at industry events or in articles about mobile advertising and LBS.
The only way to reconcile the brand and agency desire for targeting and reach in mobile is to essentially do what Yahoo has done on the PC: create a dynamic ad serving platform into which the creative elements and offers are poured and which can then assemble those elements in real-time according to the targeting parameters, location and context of the end user. Google has also done a version of this online with its "local extensions" offering in AdWords. 1020 Placecast also does this to varying degrees in its campaigns.
The dynamic ad server in the middle is the key to realizing the targeting benefits of mobile and providing the scale that large advertisers need to take the medium seriously.