Ray Saintonge wrote:
A key factor in distinguishing between a publisher and an ISP seems to be editorial control, and oonsciously active participation in the editing process. An ISP who is told that there is something illegal about a page can easily remove it as a result of being so told. Being pro-active in this may be more characteristic of a publisher, because it involves making our own legal decisions about whether a writing is in some fashion illegal.
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The problem here is that Jimbo in particular and the WMF in general has been very active in making editorial decisions.... particularly regarding content on Wikibooks, with deletion of substantial sections of Wikibooks content on the "orders from Jimbo". Office actions as well on Wikipedia (a somewhat controvercial subject) suggest that there is some active participation in this editing process. I'm not just talking about WMF board members that are also acting as contributors, but forceful decisions that have overriding authority and preempt objections, even strong objections by the community.
I'm not really sure where the WMF would fall into this category, but I wouldn't simply claim the WMF to be a mere service provider. I'm not necessarily saying that editorial control is wrong here, but it does have legal implications as you have pointed out.