The other week, we wrote about how to block Sidewiki users from commenting on your site. The issue was, it basically blocked all Google Toolbar users from accessing your site.
There is a new script that reportedly blocks only those who try to use Sidewiki to comment on your site, without blocking all Google Toolbar users. It named the Sidewiki Defeat and can be viewed at code.google.com/p/sidewiki-defeat.
I spotted this via a Google Webmaster Help thread. Warning, I personally did not try this, so be careful.
Forum discussion at Google Webmaster Help.