To observe the statistics of your site (search rankings, traffic, etc), create a google account (e.g. Gmail). Then go to:
http://www.google.com/webmasters/start
and log in.
Google will then ask you to "verify" that you are the owner of the website for which you want to see the traffic. You can either do this by adding a metatag into the code of your index.html file, or you can upload a file with a codename they give you.
Since Plone doesn't really work on HTML or have an index.html page, I created an empty text file with the filename given to me by Google on that verification page. I tried to upload that to this site, but Plone objected that the file was empty. So I just added the html tag <head>, and uploaded that.
Then I clicked on the "Verify" button at Google, and apparently it checks to see if you added a file titled with the code they provide you (thereby implying that you are the owner of the site). It worked fine, and I was immediately privy to all sorts of interesting aspects of Google's ranking of this page - the top 100 keywords, the traffic each week/month, etc. Very very cool. A few sample screencaps below:
However, I noticed that the "verification" file that I uploaded to Plone was visible as a new tag at the top of the page. Harmless, but uncosmetic (pic below).
However, since it's a file (and not a "folder") I couldn't really make it "private". So to prevent it from being seen, I went to the main Plone page, switched to Contents view, and got the listing of all the objects at the root folder. I then clicked on the "verification file" and chose "change state".
In the "change state" window, you are allowed to add a date which will "publish" the file, or a date after which it will "expire", and become invisible. I entered a date prior to today a chose "expire", and it automatically made the file "invisible". Google rankings can still see it (since it's still "there"), but it's not displayed in the Plone site, so regular people browsing the site won't see it. That's just what I wanted.