Webmaster Tools Keyword "Significance"

Google Webmaster tools seems to have added a new significance bar next to each keyword found on a site recently.
Here's an interesting screenshot, I would never have guessed the plural version of the word was being considered more significant.

I can't find this feature. Where did you find it exactly, does it have a name?

Are you already using Google Webmaster Tools ?

While looking at one of my sites profiles, I see it on the dashboard and if I go to Your site on the web -> Keywords from the menu on the left.

Okay, thanks. I found out why I didn't see it, I still hadn't verified my site.