Apple's iAd network is in serious trouble at the moment, a variety of industry sources suggest. Several developers mention that fill rates for iAd fell sharply after the New Year; in particular, two separate developers say that their rates dropped from 18 percent to just 6. In some instances apps are said to be going without any iAds, despite the fact that other mobile ad networks are delivering near-total fill rates. Even some of the more positive cases are said to be showing a slip in rates.
