When I read the Dutch license text: http://www.openstreetmap.org/copyright/nl, it still states that the data is available under CC-BY-SA on the first line.
While it has been translated in the Wiki: https://translatewiki.net/w/i.php?title=Special:Translate&task=view&language=nl&group=out-osm-site&offset=800 it looks like something is out of sync.
The other paragraphs do mention ODBL for the data and CC-BY-SA for the tiles.
Discussion
Comment from TomH on 30 November 2012 at 13:59
The Dutch translation was only changed on Monday, and there hasn’t been a sync from Translatewiki since then - that usually happens once a week or so, typically at the weekend.
Comment from Sanderd17 on 30 November 2012 at 20:18
Oh, that way. strange coincidence. I hoped someone else would translate it. but today I became inpatient and went to look up the translation myself. To find out it has been translated but not visible on the main page.