Google has launched their latest feature called Sidewiki. Sidewiki is basically a web 2.0 tools where users can add on to the Google Toolbar that allows users to comment about any site, directly on that site, via the Google Toolbar.

With Google Sidewiki, users can leverage expertise and knowledge of other users and it is also an easy way of sharing their insights with anyone about any page on the web.

As per Google Blog:

In developing Sidewiki, we wanted to make sure that you’ll see the most relevant entries first. We worked hard from the beginning to figure out which ones should appear on top and how to best order them. So instead of displaying the most recent entries first, we rank Sidewiki entries using an algorithm that promotes the most useful, high-quality entries. It takes into account feedback from you and other users, previous entries made by the same author and many other signals we developed. If you’re curious, you can read more on our Google Research Blog about the infrastructure we use for ranking all entries in real-time.

Under the hood, we have even more technology that will take your entry about the current page and show it next to webpages that contain the same snippet of text. For example, an entry on a speech by President Obama will appear on all webpages that include the same quote. We also bring in relevant posts from blogs and other sources that talk about the current page so that you can discover their insights more easily, right next to the page they refer to.
We’re releasing Google Sidewiki as a feature of Google Toolbar (for Firefox and Internet Explorer) and we’re working on making it available in Google Chrome and elsewhere too. We also have the first version of our API available today to let anyone work freely with the content that’s created in Sidewiki.

If you’re ready to start exploring the web with Google Sidewiki, visit google.com/sidewiki to download Google Toolbar with Sidewiki and contribute your own entries alongside pages on the web.