Export podcast subscriptions from iOS podcast app as OPML
I've been looking for a way to do this, but can't find a way to do it directly. Here's a workaround.

If you sync with iTunes, then you can export the OPML files from iTunes:  

In iTunes 11, open Podcasts and then choose File > Library > Export playlist, then select OPML format.

Or, right-click on the Podcasts entry in the side bar (if the sidebar is not showing, click View > Show Sidebar, select "Export...", then select OPML format.