Where RSS feeds deliver text content, Podcasting uses an RSS feature called "enclosures" to allow readers to subscribe to audio or video content using RSS. There is even software available-dubbed iPodder-that will automatically pull content from an RSS reader when it becomes available and automatically upload it to an Apple Computer iPod or other MP3 player.
Interestingly, one of the driving forces behind Podcasting has been former MTV v-jay Adam Curry, who helped develop Podcasting software and created the first Podcast "show," called Trade Secrets, with noted blogger and software developer Dave Winer. The idea took off. In a matter of months, a Google query on "Podcast" has gone from close to zero to more than 45,000 results.
Today, Podcasts are where blogs were at the beginning: loose, homemade and mostly done for fun. But popular Weblogs have already begun to experiment with Podcasts, so expect cutting-edge business publishers to jump on board shortly as well.