I often spend my summer holidays there and began now tracing roads from Yahoo-imaging, adding items. I also have a few gps logger tracks from last year I used e.g. to trace the new part of the E-65. The tracks also proved that the Yahoo images match very well.
When hopefully again there next year, I will add names to roads and places and improve classification.
Update 26.09.08:
I've added plenty of data, trying out possibilities and getting used to JOSM and some handy plugins. I also begin to add buildings. Next time I'm there, I've plenty to check. :-)