The equivalent, in podcasting news, of Conan O'Brien leaving NBC for TBS

Gruber. Photo: PED

FORTUNE -- On Friday, Daring Fireball's John Gruber, one of the most influential Apple (AAPL) commentators on the Internet, began the latest episode of his Talk Show podcast by launching without preamble into a riff about Andy Pettitte's return to baseball.

No surprise there. Gruber's podcast style is as idiosyncratic as his widely-read blog, and he'll use any excuse to talk about his beloved Yankees.

What was surprising was that after nearly two years and 90 episodes with Dan Benjamin's 5by5 Network, Gruber was podcasting from a new venue, Mike Monteiro's Mule Radio Syndicate.

In the absence of an explanation from the principals, the blogosphere rushed to fill the void with speculation about what had just happened; there were hundreds of posts on Hacker News alone. Among the theories put forward overnight (and collected by the candler blog's Jonathan Poritsky):

• A falling out (believe it or not) over a pre-WWDC batch of Talk Show t-shirts
• A dispute over the division of proceeds from 5by5's new iPhone app
• A disagreement over who owes whom more for the other's fame and prominence
• A divorce after one or the other partner grew tired of their on-air relationship

"I am honestly surprised at how bummed I am about the @danbenjamin @gruber break up," wrote @joshuaaleonard, in one of dozens of Twitter posts. "You guys were my favorite part of the week."

Most long-time listeners wished the new Talk Show well, but the consensus among those who caught the first episode on The Mule (title: "What if the Dolphins Had Thumbs?") was that without Benjamin to keep him on track, Gruber tended to go off the rails.

The iTunes customer review voted most useful Saturday morning pronounced Episode 1: "Unfocused, uninteresting and unlistenable."

Neither Gruber nor Benjamin returned our requests for comment. We'll try to keep an open mind.

Meanwhile, you can hear Gruber on The Mule here. You can get links to his old 5by5 podcasts here. You can hear a clip of Gruber and Benjamin's last awkward signoff here.

UPDATE: Benjamin on Monday posted a four-minute message about the end of Talk Show. He points out that it actually stretched back 120 episodes, wishes Gruber the best with his new show and tells listeners where they can find it. See Special Episode No. 6: Regarding the Talk Show.

Below: A song about the breakup by Jonathan Mann, the Song-a-Day guy.

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