who "owns" podcasting?

It is reported that Adam Corolla has spent $650,000 protecting his right to podcast.  In every business, there is an increasing number of threats by so called patent trolls.  In this case, a company called Personal Audio claims to have invented podcasting.  This week a government board revoked 5 key parts of the patent which would make it more difficult for them to sue podcasters for infringement. The Washington Post covered the story.