The Diffusion Group released a report claiming huge market for Podcasting. Quoting from
Om Malik’s blog

TDG’s new report, Podcasting: Fact, Fiction and Opportunity, suggests that between 2004 and 2010, the use of podcasting among US consumers will enjoy a compound annual growth rate (CAGR) of 101%.

Rssblog also made fun of the report.

Given that I’ve came up a few of the market sizing estimates before in my life time, I want to share a few tricks. One of the best way to get a huge market size number is to take an existing related market and count that in the “new” market. If you think that the old market will be replaced or augmented with the new technolgy, its can be a somewhat defensible estimate. I dont have access to the research report but I bet that if you count in the audio books market and factor in somesort of e-commerce penetration rate (its a $800M market based on a businessweek article I dug up) you can certainly claim that Podcasting is a billion $ market eventually. It all really depends on how you define Podcasts - commercial recordings or only amateur “audio-blogs.”

Also a random thought. . . I bet the legal/trademark department of Apple is having a hard time trying to manage this “Podcasting” phenomenon. I wonder if the fact that Podcasting/Podcast is not an Apple trademark will adversly effect its ability to defend “iPod.”