You might be asking, "What is a Patent troll?" According to Wikipedia a Patent troll "is a person or company who enforces patent rights against accused infringers in an attempt to collect licensing, but does not manufacture products or supply services based upon the patents in question, thus engaging in economic rent-seeking."
This is exactly what the company Personal audio has been doing to various podcasters. It argues that one of their patton 8,112,504 covers all podcasts and anything that contains episodes over the internet.
Personal Audio has tried to attack the Podcasting business by filing lawsuits against different podcasts including Adam Carolla who has one of the most popular Podcasts. The idea of the Patent troll is to have podcasters roll over and hand over the money But Adam Carolla started the "Save Our Podcasts Legal Defense Fund."
With the help of fans and other Podcasters such as Marc Maron this fund is raising money and awareness to help fight off these patton trolls.
As for now the case with Adam Carolla and Personal Audio has come to a hault but the Patent they have still exists and there is nothing stopping them from potentially trying to attack and shakedown smaller known Podcasts.