Advertisements or other types of targeted information are delivered to a set-top box or other user interface device of signal distribution system. In one aspect of the invention, a detection server of the system detects at least one cue associated with a first media stream, and generates timing information from the detected cue. The timing information is signaled to the interface device. An advertisement server of the system generates a second media stream containing targeted information for delivery to the user interface device. The user interface device switches from the first stream to the second stream based on the timing information. The timing information may also be signaled by the detection server to the advertisement server, for use in controlling generation of the second stream.