For information about arc42, have a look at www.arc42.org
Some simple XSLT-Scripts to convert the confluence-export of arc42 to freemind-format.
You need to use the current RC (1.0.0-RC5) of freemind to open the generated mindmap.
To execute the XSLT, I used SaxonHE (see example.sh)
To make it work, unpack the confluence data to confluence/
When you open the mindmap, it expects the attachments directory of confluence besides the mindmap file