On 9/23/09 Google launched an in-browser tool called Sidewiki which essentially established an outer shell to the internet allowing users to leave comments not on original landing pages, but within a sidebar next to it. This caused a bit of a stir amongst web site owners and some brand representatives as it signaled the loss of control over what information could be shared on a given website. Afterall, if the sidewiki lives outside of the site, it does not allow webmasters the ability to delete comments.
As time has passed, Sidewiki actually hasn't picked up much stream. Having done a quick audit of the top brand websites, very few have a significant number of entries other than a sprinkling of SEO blackhatters trying to game a system that is yet to become popular.
That being said, there are a few discoveries I've made in the last few days that I thought I would share in regards to defending your site again malicious Sidewiki comments:
1) Create a Master Sidewiki entry: As you'll see from my screenshot above, I've added sidewiki entries to this blog. The entries that have a light green background are called master entries and will always be located at the top of the window. Although this isn't going to let you eliminate negative entries on your page, it will at least let you have the first word within the sidewiki and (if you choose) fill up the entire sidewiki above the fold with your own comments.
2) Block Sidewiki with httpS versus http: Most entities tend to stay away from hosting a "https" site due to various reason (poor SEO, slow load times, etc) however I've noticed that Google Sidewiki will NOT work on these sites. Do a quick check on banking sites such as Chase.com or Fidelity.com and you'll see it in action.
Addition Resource (Not Verified): http://www.willmaster.com/library/web20/sidewiki-comment-protection.php via @saraburton.