asciiphil
(Phil! Gold)
4
I just learned about this the other day, but you can upload your files (GeoTIFF in WGS 84 only) to http://whooms.mapwarper.net/, which will then give you a WMS link that you can use with JOSM’s wmsplugin. I just pick “Rectified Image” from the WMS menu and paste the WMS URL into the field there.
The other thread is http://forum.openstreetmap.org/viewtopic.php?id=7678.
Naturally, if you’re tracing from the images, you need to make sure their licensing terms are compatible with OSM’s.