While reading Charlene Li's post about the new podcast support for iTunes yesterday, I noticed---for the first time--Forrester's forecast for podcast usage for 2005 is 300,000 US households (report published in March). Now, if you follow podcasting you'll recall a report last month (David Berlind, Dan Gillmor, IT Facts) from the Pew Internet & Life Project that reports about 6 million podcast listeners in the U.S. That’s 20 times greater than what Forrester reported! As David Berlind noted, it's not clear-cut what can be classified as a podcast. But even if both firms took different approaches, a discrepancy this wide means somebody is really off.
I would side with Forrester on this one because I can't imagine this relatively new technology to have taken off this fast, even if RSS and iPods are all the rage. Unfortunately, I don't have client access to the Forrester report to compare its methodology with that of the Pew study to draw a better conclusion, but I suspect it's similar. What do you think?