I'm not too happy with the geocaching module as it stands. It doesn't do enough to be helpful. So - I've started looking at some changes in direction:
We need to be careful to stay within the geocaching.com license. This does not permit the users to publish data from geocaching.com open to the public (from what I can see).
Parsing standard GPX is OK. Parsing the geocaching addons probably isn't. I believe that linking to geocaching.com may be acceptable - but I'm not sure.
So - I think that the next change could instead be:
I'll have to check with geocaching.com about what they are willing to allow for linking.
Current code is in the gpx branch of http://dev.chrissearle.net/git/geocaching.git