Dailysonic has discovered that Apple is caching the podcasts and feeds published through its podcast directory.

Apple has made a number of odd choices with its podcasting support in iTunes; this is just one of them.

If I were publishing a podcast, I'd be glad that Apple cached it. At last count, Apple had sold more than 400 million songs through iTunes. If one percent of that traffic decided that they wanted to sample my podcast, my server would explode. Podcasts tend to be rather large files; far larger than the stuff pushed out by my regular feed.

On the other hand, sophisticated podcasters like Dailysonic depend on advertising revenue, dynamically inserting ads into the stream and carefully tracking download statistics. Having Apple cache the streams presents real problems.

I couldn't find any mention of caching on the Apple podcasting site or its technical documentation.

It should be relatively easy for Apple to allow publishers to opt out of Apple caching.