Advertising over the mobile web is no new development, but it’s certainly starting to look like a more profitable one, thanks to Apple’s iAd. In just the first day of Apple’s in-app advertisements, one lucky developer earned $1,372 in revenue. The campaign boasted impressive numbers across the board (besides revenue), including an effective cost per thousand (CPM) of $147.55, and an exceptional click through rate (CTR) of 11.8%. Cases like these, though rare, have led some mobile analysts to speculate that the future of advertising success resides on the small screen. The wild success of the first round of iAd promotions corroborates this prediction, as does the $416 million invested in mobile advertising in 2009.

But one very critical point of question remains, is this success just a fad? iAd has exceeded the expectations of many advertisers thus far, generating surprising earnings for developers (and Apple), but are consumers more likely to click due to the novelty of these interactive apps? Is this a short-lived popularity that will soon fade?

If Ad-Mob’s revenue figures are an accurate indication, the stellar performance of iAd may be momentary. While AdMob led the mobile advertising market in 2009, grossing a total of $59 million, many actual advertisers’ earnings are minimal—less than $10 even—and some advertisers even report an overall loss for campaigns. It’s too early yet to say whether or not iAd will share this fate, but most analysts expect their results to flatline in the coming months.

That said, even if iAd revenues drop-off somewhat in the future, certain application categories clearly yield higher earnings, and may continue to do so, whether because there are fewer competitors, the market is less saturated, or the services appeal more to mobile users. Fields that are currently enjoying greater revenue yields include finance, social networking, and education. Furthermore, while the preliminary earnings from iAd may prove misrepresentative in the long run, there are undeniable advantages to advertising over the mobile web, such as the ability to interact and engage more with a much more targeted audience, as opposed to the former spray-and-pray advertising model. So while mobile web users are likely to lose some interest over time, particularly as they become more saturated, reaching a plateau in mobile advertising revenues should not undermine the efficacy of these campaigns, and the potential that they represent for many advertisers and developers from all fields.