Just over eight years ago, Apple introduced podcasts as an integral part of iTunes, and along the way, it helped shape how we consume information and entertainment. Now, the company's announcing a rather significant milestone in the field: something to the tune of 1 billion subscriptions. Of course, the road to this achievement has been marred with some unpleasant bumps, but today's all about celebration. In that spirit, Apple's highlighting some of its most popular podcasts of all time, such as This American Life, TWiT and All Songs Considered, along with up and coming programs such as The Alton Browncast. Granted, it's not quite the fanfare as you'll find when Apple celebrates App Store milestones -- the most recent being 50 billion downloads -- but it's hard to get bent out of shape given all the free content. So grab your earbuds and do some celebrating. Cupcakes are entirely optional.