As our world has grown more mobile and related technology has evolved, podcasting has become a mainstream form of continuing education—including for marketers.

"Podcasts are a new form of continuing education, making it possible to 'audit a class' in any subject just by listening on the go," states the following Marketing Podcasts infographic.

And unlike in the early days of podcasting, today's podcasts are easier to download and listen to on smartphones and mobile devices.

For example, iTunes now has 250,000 podcasts, up from 200,000 in 2010, and Apple has more than one billion subscriptions to podcasts via its iTunes app.