this doesn't seem to be too complicated of a plugin, it just takes the player positions x,y,z and exports them to a file named markers.json every so often. The plugin author for this seems to have vanished like a fart in the wind, so I am hoping someone who reads this will take pity on all of us who use this plugin for our maps and don't know enough to write a new one ourselves. This may even be simple enough to just change 2 or 3 calls and be done, but I don't know. the source for the plugin is here: https://github.com/mrsheen/minecraft-hey0-plugins/blob/master/mapmarkers/src/MapMarkers.java
This was done quite a while ago - search http://plugins.bukkit.org for it - I just never posted in here again. It now even supports multiple worlds
