I’ve got an idea:
Make a geoserver extension to interface it with mapnik.
so it is possible to have a full tile generator too in OGC standard and with advanced protocol like WMTS plus system caching.
i think it’s very usefull for users that need custom tile map, cartography designer, or who want to contribute for making more beautiful osm map with the philosofy of open-data / source.
in addition it will be very simple to configure and to set-up the server / system.
this is the summary of my idea. 