Proposal: OSGeo Cartographic Library
GRASS, QGIS and others are in the need of their own map printing tools for high quality output but these projects should not start from scratch. There is a wealth of underlying code already in Mapserver, Mapguide etc which could be re-used in the terms of their respective licenses and certainly of programming language compatibility. A joint OSGeo Cartographic Library comes to mind.
See also the ongoing related discussion!