I have read a number of controversial points made concerning the viability of Wikipeda's links, in terms of links fromt the site raising your own site's PR. What are some of your thoughts on the subject?

Wikipedia uses "nofollow tags".

Here is what Google had to say:
http://googleblog.blogspot.com/2005/01/preventing-comment-spam.html

yes, wikipedia uses no follow tags on their links so it is not picked up from SE spiders, so it will not have any effect on page rank.

but having your link on wikipedia is good exposure. while it is not going to raise your PR or have any SEO effects, it is a good source for traffic and is especially valuable because it brings relevant visitors to your site if your business is ecommerce.

I'm quite new to this, but someone (semi-amateur SEO) pointed out that we really don't know that much about SE's. It is possible that they still attach same value to the link. (Perhaps other SEs value it and Google doesn't.)

...just food for thought. (Of course they may also lower the trust rank score for a page/site that has too many inbound links with nofollow.)