How can you tell that PR is not passed on? Not that I think it has anymore clout than any page with the same PR. But I can't see why Google would block Wiki links.
However I've found it is a good source for traffic at least in academic areas. Also in my field I don't find that editors delete quality links.
A while back I decided it would help me more to join them so I've written some info in my field and linked to pages of mine where appropriate. I've also linked to some other quality pages from wiki articles. But then mine isn't a competitive topic.
It does look like wikipedia is floating to near the top on many searches. It's the power of the size of the site just like those topics 'about' stuff tend to rank in the top spots.
I am convinced large content sites have an advantage. There is a lot of power in internal linking.