Yes, it has been confirmed by the Wikipedia Admin, and I just
read it on the Digita Point forum.
And here is the exact post there:

It was decided to switch on the nofollow attribute for all external links in the English Wikipedia. This has been an option for a while, and it was done now because of an influx of spam and talk of an SEO competition targeting Wikipedia. Whether it will stay this way for a while or indeed permanently, no one is really sure. If some links have not changed, I believe this is due to WP’s caching system, and they will be nofollow soon.

In any case, adding links to Wikipedia to promote websites is strongly discouraged. They will most likely be removed, and if continued you can be blocked from editing.

Hope this helps to clarify.

the wub - Wikipedia admin

In terms of SEO the NOFOLLOW will be bad news for many sites,
but the links that remain on Wikipedia will still bring traffic. And
what is better according to you? Higher PR ranking, or traffic?

The opinions vary wildly and if I had to choose I’d like both of
course. Getting the traffic only is still all right - if your link
remains in there for the long run.

Talk to you soon