What makes a good podcast?

It seems that everyone is podcasting these days. The podcasts I've listened to have had a range of formats. Some are better than others. Listen to these examples for formats that work:

Educational briefing
"Debunking the Hype about Skype," part of Burton Group's Inflection Point series, features Senior Analyst Irwin Lazar talking about controversial issues surrounding this popular Internet-based communications application. The podcast demonstrates knowledgeable and unbiased analysis.

Conversational dialog
"Making an Online Community Tick," first of a Knowledge@Wharton's series hosted by Kevin Werbach, features a panel discussion among three industry thought leaders. It not only promotes Werbach's conference but also provides visibility for key participants.

Ad hoc interviews
EXPO Magazine Podcast Episode #02, second in a weekly series covering "tradeshow tips, tricks and trends," is a hosted radio show format, where the producer interviews EXPO editors and industry experts. It promotes upcoming issues and gives advertisers online exposure.

Which format is most effective depends upon your communication goals. In my view, a good podcast is:

• short (15 minutes or less)
• conversational (features more than one person)
• moderated (identifies speakers and controls content)
• instructive (gives take-away tips)
• glitch-free (plays without interruption)
• lively (with animated speakers)
• production-quality (musical interludes, etc.)

If you've heard a podcast that sets the gold standard for format, content and quality, post it here.