Musings from Mars > iTunes Interface Controversy
A little exposed part of the iTunes interface:
I just figured out that iTunes imports & exports OPML! Who knew? (iTunes doesn't always expose advanced functionality, but this keeps things simpler for non-power users.)
To import OPML, just go to File > Import... and select the OPML file.
To export OPML, select the "Podcasts" item in the left hand column (of playlists/sources/etc) and then go to File > Export Song List. You may then choose Plain Text, Unicode Text, XML, or OPML from a popup menu.