You can’t and the web is full of whining from site owners about how this space, being out of their control, is not fair. It’s Google, so best we get over it, folks. Regardless of whether it is fair (since when is the web fair), we’re all best off learning to deal with it. This is quite similar to what StumbleUpon and Delicious enable, however, because it’s from Google and it’s more visible on pages, it’s a bigger deal.

Two questions and answers.

One, will it catch on? Yes. It could take a few years to get big, as Twitter did, but because it’s on Google’s Toolbar, it has a seductive interface (a little tab on pages with comments) and can become viral. As users spread it, it’s going to grow.

Two, what best for marketers and site owners do? First, claim your site. Second, monitor and respond to comments. (With the Sidewiki API available, it will likely soon be built into tools like Radian6.) And third, add your own social features — now.

If you add social features, such as ratings and reviews, comments, and forums to your brand site, your media site and your blogs, your visitors will find them more convenient. They will generate discussion, but discussion you can moderate to your own standards. And if the interesting discussion is on your site, people won’t be compelled to comment with Sidewiki.