I would have sent this to the debian PD maintainer, but it appears the package is orphaned right now.
If you the attached puredata.xml file into /usr/share/mime/packages/ and then run 'sudo update-mime-database /usr/share/mime/packages' programs like rox-filer and nautilus will recognize the application/x-puredata mimetype, allowing the association of the files for point and click opening.
I joined the list in order to forward this info, so please pardon me if this has already come up before. Is this something that would be good to include as an optional installable part of pd for those who use this mime update method?
Also, I have embedded the expat xml parsing library into a pd external in order to import objects from svg documents edited in inkscape into pd structs, what would be the best way to share this with others once I get my code cleaned up enough for distribution? (so far, between the external and a pd patch I can import three sided shapes accurately, accounting for scale / translate / shear / rotation data).