[OSM-legal-talk] ccbysa Prominence clause

[Richard Weait]

Recent OSM-derived sites have included beautiful vanity logos on the
map.  As an example, the recent isochronous map of Paris:

http://www.isokron.com/default/
Has a beautiful, bright "isokron" logo and link to their site.  But I
wonder if this meets with the Prominence clause of our ccbysa license?

The full text of the cc-by-sa (v2.0) license includes this clause
regarding "prominence"

"
Such credit may be implemented in any reasonable manner; provided,
however, that in the case of a Derivative Work or Collective Work, at
a minimum such credit will appear where any other comparable
authorship credit appears and in a manner at least as prominent as
such other comparable authorship credit.
"

http://creativecommons.org/licenses/by-sa/2.0/legalcode

In our example above I'm comparing the isokron logo-link with the
OSM/ccbysa link at the bottom of the page:

large colour "isokron" logo
- approx. 300x76 pixels
- bright colours
- link to www.isokron.com

and OSM / ccbysa credit
- approx. 175 x 10 pixels
- grey on white
- links to ccbysa text and openstreetmap.org

The OSM / ccbysa link text appears to be fully compliant with our
guidance on the wiki[1].  It has links to both OpenStreetMap and the
CC license text.  But the prominence?  Not quite as good.

The isokron logo is ~13 times larger than the OSM/ccbysa link.
The isokron logo is colourful and the OSM/ccbysa link is monochrome.
The isokron logo is on the map and the OSM/ccbysa link is below the map.

My questions to legal-talk are:

1) Is this a situation where the prominence clause should be applied?
And if not, when should the prominence clause apply?
2) What guidance should we offer to good members of the OSM community
who wish to have a large beautiful logo on their map?

Best regards,
Richard

[1] http://wiki.openstreetmap.org/wiki/Legal_FAQ#I_would_like_to_use_OpenStreetMap_maps._How_should_I_credit_you.3F
Oh.  That link is terrible.  Here is a shorter link.  http://ow.ly/1v4Z2