News for hackers. Stuff that matters.
Re:Introducing Prose: A Content Editor for GitHub by cedrichurst on Monday June 25, 2012 @10:49PM (#4159980)
It uses backbone routers, so try something like:

http://prose.io/#MyOrganization/my-repo

Worked for me.

Re:Introducing Prose: A Content Editor for GitHub by why-el on Tuesday June 26, 2012 @07:58AM (#4161336)
Thanks. I ended up creating an issue for this and they mentioned a url like yours, except that I needed to append a master at the end, like @BHSPitMonkey suggested bellow.
Re:Introducing Prose: A Content Editor for GitHub by BHSPitMonkey on Tuesday June 26, 2012 @02:58AM (#4160645)
Note: You also need "/master" at the end, or whichever branch you intend to work on.