Yeah it’s kind of the whole point of the OpenStreetMap project (in the UK at least) Up until now it has been true that anything resembling a decent detailed map must have been derived from Ordnance Survey. This was always the frustration with maps in the UK… until OpenStreetMap came along. We create our maps from scratch, or using copyright-free sources so that we can release the maps with an open content license.
When you publish OpenStreetMap maps Ordnance Survey is not involved. Provided the publisher mentions OpenStreetMap (which they are required to do under the terms of our license) then ordnance survey have nothing to complain about.
This is something publishers should be aware of. Now you can publish a decent* maps. Hurray!
(* in areas where we have achieved a decent level of completion)