Read The RestA couple of months ago we wrote that podcasting was under threat from a patent troll. At that time, a patent troll named Personal Audio LLC had sued three podcasters and sent demand letters to a number of others. Since then, Personal Audio has filed two new lawsuits—this time against CBS and NBC. It has also sent additional demand letters to small podcasting operations. We’ve written often in the past about how patent trolls are a drain on innovation, and this latest troll is no exception. Since many podcasters barely make a profit, or simply do it for love, a shakedown from a patent troll…