YouTube is removing about 1 in 12 of its popular videos, according to stats collected by YouTomb.
YouTomb is tracking the videos because of concerns that YouTube may be pulling videos that may incorporate copyrighted material under fair use.
Currently:

223,187 YouTube videos are being monitored by YouTomb;
4,395 of these videos have been taken down because of copyright [...]

blubrry’s Todd Cochrane announced today that his company was removing more than a hundred podcasts from its service and banning sites because of problems with “podspam”:
This morning I instructed our CIO to have all shows that were using a RSS Feed generation service hosted by trafficgeyser.net and mypodfeeds.com to be terminated here at Blubrry.com
From [...]

MessageLabs reports that spammers have introduced MP3 music files into their expanding toolbox of stock spam techniques, with 15 million emails identified in October 2007.
We’ve been concerned for a couple years about the potential of audio spam. With the rise of speech-to-text based search in products like PodZinger, it’s only a matter of time before [...]