Not neccessarily. It depends on the topic and on the quality of your content. The key is that Wikipedia will only allow sites adding to the article with more information.
I have two of my sites in Wikipedia for 5 months and no mod has tried to remove them. It is too early to tell if being on Wiki does me any good but it gives me some 10 - 20 visitors each day, targeted visitors, I would say.
On the other hand, Wikipedia hasn't helped me to rank higher with Google. In fact, I don't see how it could - it uses NOFOLLOW on all external urls.