The Adform iOS SDK by Vladas Drejeris enables API communication to integrate advertising services. Basic antegrations include inline ad, overlay ad, intersitial ad, adhesion ad, and video ad. Resources include advanced integrations and release notes.
When it comes to mobile computing most organizations are relying on applications that are running on a number of devices that remotely access data via an API. The folks at Usablenet are leveraging RESTful APIs to make the case for the exact opposite scenario.