I use QGIS 1.4.0 to import a layer which is basically a road network converted from an .osm file to a PostGIS database table by osm2pgrouting.
I have skimmed through the documentation, but I am still not sure:
What happens when I edit features of such a layer in QGIS? Can I somehow write the changes back to the database?
Edit: This could be the answer, isn't it?