iMedia Connection has an article by Sarah Keefe:
Mobile ads physically can’t emulate their bigger web cousins due to restricted screen real estate.
There’ll be banner ads but much smaller than on the web. There’ll also be text ads but they’ll likely be squeezed into the body of a page that’s highly relevant. Expect creative directors to explore new ways to get the message across– just as they did when web advertising was in its infancy. In the mobile arena, you might see voice ads stream while you’re browsing a WAP site or ads being delivered while interstitial pages are waiting to be downloaded.
Mobile marketing campaigns can be fine tuned.
Imagine having valuable information, such as the consumer’s country and network. That knowledge can help fine tune marketing campaigns enabling them to effectively target a particular region and track local success. Advertisements also could be targeted to a user’s handset make and capability. So, if you sell games for a particular device type, only people with compatible handsets will see your ads.