Quote of the Day - I don't know anything about music. In my line you don't have to.
As Denise Howell has warned, it was just a matter of time. A state court in New York ruled (subscription required) that prosecutors do not need to show intent to prove criminal violations arising out of the sale of "DJ remixes" using copyrighted material.
Take away for a moment that this case is criminal (which is easy to do because without intent, the criminal statute looks more like contributory copyright infringement), and take away that this is a "DJ remix" (which is likewise easy because some podcasters have used snippets of copyrighted music). What you're left with is liability for using copyrighted music.
Justice Lewis Bart Stone issued a 22-page sentencing memorandum in this case, People v. Colon, 3962/04 in the New York Supreme Court (NY's lowest court, and I haven't been able to locate the decision online), and spent five of those 22 pages explaining his views on copyright infringement, according to the New York Law Journal article cited above.
Before you add music to your podcasts, check to see if it's copyrighted. If it is, don't use it. There are other alternatives out there.