Initially I had no idea, but then I remembered PodNova.
Aside: I’ve since learned that iTunes supports OPML import / export, but still think PodNova is the better way to go — online centralized repository of all your podcast feeds VS saving and moving OPML files between computers.
I’d written about it a few years ago when I was looking into a text-to-speach solution for my blog: How to convert your blog post into a podcast.
Basically, PodNova is a service that you use to subscribe to all of your podcasts. Or, you can stream your podcasts directly to your computer (or mobile device: iPhone, iPod Touch, etc).
But, if you want to keep all your computers synchronized, you simply point your iTunes subscription at ‘your personalized’ RSS podcast feed. Done.
The result is that you now have one feed to remember, but that feed now contains ALL your podcast subscriptions. All you have to do is subscribe to your PodNova feed, sit back, and enjoy your podcasts. Once per computer.