Google Toolbar 6.4 for IE and Firefox adds a feature that lets you share web pages using social networking sites, mail services, bookmarking services and other sites. You can select your favorite services from the settings page or repeatedly click on one of the options to bring it to the top of the menu.

If you share links using Twitter, you'll notice a new URL shortening service: goo.gl. "Google URL Shortener at goo.gl is a service that takes long URLs and squeezes them into fewer characters to make a link that is easier to share, tweet, or email to friends. The core goals of this service are: stability, security and speed." The service is only used by Google Toolbar and FeedBurner, so there's no web interface or API for goo.gl.

Nice tool to share websites, after years Google has re-invented the wheel, hehe

I like to see more from the new URL shortener goo.gl, sad enough the service doesn't work from the toolbar right now

Until Google dumps this or provides an opt out, web site owners who'd like to retain control of what appears on their own site can block all Google Toolbar users by adding the following to their htaccess file. The "notoolbar.php" points to a file explaining Google's bad behavior and instructing the visitor to uninstall Google Toolbar in order to proceed. You can create your own file and name it whatever you like, just be sure to change the code below to make it match the file name you've chosen.

RewriteEngine On

RewriteCond %{HTTP_USER_AGENT} GTB [NC]

RewriteRule .* notoolbar.php [L]

This is of course a working solution to protect your website against unwanted comment via the Google Sidewiki, but in fact you block visitors using the Google toolbar. I'm afraid the biggest "side" effect will be a lower number of total visitors.
Sorry guys from the SE roundtable, this is not a workaround...