Googlers, John Mueller and Susan Moskwa put together a very comprehensive Knol page on Google Webmaster Tools verification.
So if you are new to Google Webmaster Tools and you are about to verify your site with Google Webmaster Tools.
You can already see several revisions to this knol page, including one waiting in moderation by Cristina Wood.
Who cares? Well, besides for this being very comprehensive, you might want to investigate it for your own stuff. Matt Cutts of Google wrote Four Things You Need To Know About Knol, where one point was:
My personal conception of Knol is that when you want to write a quick article or put some information on the web, Knol is a great place to do it.
That being said, Knol launched in July of last year and is still trying to gain traction on Wikipedia and the likes.
Forum discussion at Google Webmaster Help.