Google introduced a new service called Google Sidewiki some time ago which basically gives Google account owners the opportunity to share their views and opinions about a website, service or page with the rest of the world. Google Sidewiki was integrated into the Google Toolbar. An unofficial bookmarklet appeared on the web soon thereafter allowing users without the Google Toolbar to view the comments left by other users. Still, only Google Toolbar users were allowed to leave comments about a website.
The Firefox add-on Google Sidewiki Client adds the full Google Sidewiki functionality to the Firefox web browser. Google Sidewiki information are added to a new sidebar which can be displayed by pressing the Sidewiki button in the status bar.

Users of the add-on can read the reviews and notes that have been posted by Google users about the website they are on. A little bit unfortunate is that the information are not automatically refreshing. The information are only refreshed if the button in the status bar is pressed again. This needs to be done for example when switching tabs or loading new links in the active tab that lead to other pages or websites.
Users who are logged into their Google account can submit their own reviews of the website, express their opinion about other reviews by voting for or against them, share reviews or report abusive reviews. It is basically the complete Google Sidewiki client in the Firefox sidebar.
The add-on is in an early stage which becomes apparent in two key areas. The first is the already mentioned auto-refresh that is missing. This makes the add-on cumbersome to use. The second are the missing controls in the sidebar. It is not possible to go back or forth and the login screen breaks the layout of the sidebar.
Interested users can download the Firefox add-on from the Mozilla website where it is available for all Firefox 3.x versions.
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Not a bad idea in principle.
BUT…
Browsing history? I think not. I can switrch it off? I believe them, 1000s wouldn’t…
Membership verified via my mobile phone????? I think not!!
Why bloat firefox with another add-on when google just released a sidewiki bookmarklet.
here is the link:
http://www.google.com/support/toolbar/bin/answer.py?hl=en&answer=164493