Up on slashdot: http://yro.slashdot.org/article.pl?sid=07/11/13/0356203
Referencing: http://en.wikipedia.org/wiki/User:Ydorb/khobar-copyvio
On first glance, the claim appears valid; User Ydorb wrote the material in question before the book came out, there's a clear copying of the material, etc.
Ydorb says he's public-domained most of his contributions, but rightly points out that other WP contributors were involved in the apparently plagarized version, and that the WP GFDL sharing license would require attribution anyways.