Small Business Trends has taken a look at Podcasting Trends for 2007 as related to small businesses. Although the interpretations pertain to small businesses, the facts are clearly valid no matter if you are B2B or B2C.
The author sites the growing sales in MP3 phones and players - together over 320 million in 2007 anticipated. [...]

50% increase in Internet Radio Usage
11% have listened to an audio podcast (though this oddly included downloadable music, which skews the results)
20% of these are between the ages of 12 and 17
53% are under 35 years old

Now, while on first glance that makes podcasting seem like a very young trend, the converse of those numbers [...]