If you need the number of words in a particular version of a wiki article for some sort of report, here's how:
1. Sign In with your Widows Live ID
2. Navigate to the article you want to count
3. Click Edit (you wont see this tab unless  you are signed in)
4. The word count of your article is displayed in the bottom right-hand corner of your screen.
This article has 79 words BTW, according to the metric.