Personal Audio has been threatening the podcast world for a while -- the longtime patent troll claims that it invented the concept of podcasting, and has insisted that some bigger productions (such as Adam Carolla's) either cough up licensing money or face lawsuits. You may not have to worry about your favorite series going off the air in the future, though. US patent officials have nixed some of the core claims of Personal Audio's "podcasting patent" after the Electronic Frontier Foundation pointed out podcast-like shows that were running before the patent even existed. Some aspects of episodic online audio are just too obvious to be patentable, according to the finding.