Apple has a filing for making podcasts interactive (source: AppleInsider).

In the filing Apple says...

"....Podcasts of classroom lectures and other presentations typically require manual editing to switch the focus between the video feed of [an] instructor and the slides (or other contents) being presented," Bertrand Serlet, Senior Vice President of Software Engineering at Apple, wrote in the 15-page filing. "In a school or enterprise where many presentations take place daily, editing podcasts require a dedicated person, which can be prohibitive. "

To solve this problem, Serlet proposes has proposed an automated content capture and processing system where a live camera feed of a presenter can be automatically merged with a Keynote or PowerPoint presentation to form an entertaining and dynamic podcast that lets the viewer watch the presenter's slides as well as the presenter...."

This would be an interesting development when and if it sees the light of day. In the meantime streaming an audio feed to syncronised slides can be done but it is tricky or an specialist 3rd party service. Streaming video is even more complex.

NB: We recorded a two day conference for one of our clients and have the slides and audio syncronised for EUFIC at their Food In Action Conference in Brussels in November 2007. A total of 22 presenters can be listened to and their PowerPoint slides watched at the same time.