Yes,getting a wikipedia backlink is very good for a website.A dollow links gets all the link juice whereas a nofollow has a little effect.Still getting a nofollow link from wikipedia will definitely help the website.
Well, I would say every link matters even if its no followed. I don't think that there is any reason to comment over it but yes one more thing getting a nofollow link from wikipedia do counts because its an open source.
Yes Because if you write anyting on wikipedia or post something about any topic and create hyperlink in this content then there is chance to get traffic from wikipedia because if some search for the related topic and your post display in SERPs then visitor can land on your website by clicking in wikipedia link.
@Scotthiggins no it's not like that no follow links still has its own weight, if your words are true then tell me why other people are working over the no follow forums ... ?? And I guess this forum is also no follow. So my motto is to make you understand that no having a no follow link isn't a demerits but its just the link juice i.e. the seo benefits is not passed. And getting a no follow link from wikipedia has its own benefits.