The latest version of the ever-popular Google toolbar implements a new feature called “AutoLink”. It seems to be no different to the ill-fated Microsoft SmartTags that Microsoft tried to introduce some time ago.
The tool adds links to “relevant” content and service providers in your website. For example, if you quote an ISBN number on your site, the tool bar will convert it to a link to Amazon’s page on that book. Apparently maps, telephone numbers and other similar types of reference data are effected.
BBC has more on the story. (And clearly, this is a big issue for us at the BBC – as a public service provider we could appear to be promoting these services, when in fact we aren’t.).
If you want to protect your site, you can implement this nifty piece of javascript from ThreadWatch.