Hello!
I've that on Walking Papers we can "print" a map with 'bing aerial imagery', you scan it and can edit directly with osm/potlatch.
Is it legal?
I didn't find any legal information about these aerial images.
Example:
http://walking-papers.org/print.php?id=rx9v5vqb
this is in preparation for Rencontre Vaudoise du 5.3.11 :
http://wiki.openstreetmap.org/wiki/RencontreVaudoise20110305
Best regards
Stéphane