Nor would Twitter know what to do with an upspin file. The problem seems to be distributing the content, not the naming of it. Edited to add: Ideally that's

Nor would Twitter know what to do with an upspin file. The problem seems to be distributing the content, not the naming of it. Edited to add: Ideally that's what the URL is for, it should be possible to get the URL of the image on FB and post it to twitter, since both speak DNS/HTTP.