A simple file format to share brush presets. It could be a zip file with all the brushes and an xml file with some info (name/ author / email / url / year/ version/ description). When Krita opens this file it could ask the user if he wants to install the pack, if the user confirms then Krita could extract all the files to the appropiate places and refresh the presets docker. It should also be registered with dolphin so the user can install by double clicking on the file.
We are actually working on that: https://mail.gnome.org/archives/gimp-developer-list/2013-April/msg00051.html is the proposal. A group of students from Toulouse are working on the implementation.
*** This bug has been marked as a duplicate of bug 341752 ***