As part of my work on All About Symbian, I've done quite a bit about the Nokia Podcasting application which comes bundled with all their Symbian S60 phones.

You can subscribe to podcasts in Podcasting by adding their feed address manually, or you can find podcasts from a search engine.

The app also lets you add and browse online OPML podcast directories, so you can click on a podcast to subscribe to it without having to enter a URL.

So far I've added the BBC's directory:

http://www.bbc.co.uk/radio/opml/bbc_podcast_opml.opml

The US public broadcaster NPR also has a directory:

http://www.npr.org/podcasts.opml

While trying to find more of these official podcast directories, I noticed Canada's CBC website had a podcast feedback form so I suggested they set up an OPML podcast directory, and... they did! How is that for customer service? :-)

You can now browse all CBC audio and video podcasts on your podcasting software (including Nokia Podcasting) through this link:

http://www.cbc.ca/podcasts.opml

Has anyone else got OFFICIAL online OPML directories of this kind?

I know there are lots of unofficial OPML podcast addresses, but are there any other major broadcasters which host their own directory?

You might look at the various PBS shows like NOVA, Nature, etc.