Google has added a link on its homepage to promote the fact that the Nexus S is free with contract today at Best Buy, reports Search Engine Land. The notice is presented just below the search box and links to Google’s homepage for the Nexus S, with images of the phone with AT&T, Sprint and T-Mobile logos, showing that the flagship device is now available on all three carriers.

Screen Shot 2011 08 03 at 9.15.22 AM 500x320 Google is advertising a free Nexus S on its homepage

While the ad on the homepage states ‘Nexus S, a pure Google experience. Get it FREE today only.’ When you follow the link, you’re taken to a Nexus S splashpage showing that the phone is available on three out of the four major US carriers. A footnote on the page indicates that the phone is only ‘free’ with a 2-year contract.

Screen Shot 2011 08 03 at 9.15.39 AM 500x325 Google is advertising a free Nexus S on its homepage

The ‘buy now’ link takes you to a page that allows you to go to Best Buy’s online store to get the phone free, or other retailers around the world, although it seems that Best Buy is the only US store participating in the promotion. Other retailers in the UK and Europe seem to be offering the phone with normal contract options, some of which are ‘free’ or close to it.

Google advertising its own products on the homepage of the site is not without precedent, as it did very much the same thing when launching its Nexus One smartphone in March of last year as well as the original G1 phone, which was a T-Mobile exclusive.

When the G1 was launched, an ad for it was on Google’s homepage for 7 days and delivered about 800,000 visitors to T-Mobile’s site. That’s a 1% clickthrough rate going off a Compete estimate of about 99 million people who visited Google.com during that period.

The Nexus S, which just recently became available on AT&T, is Google’s flagship device that runs a ‘pure’ version of Android 2.3 ‘Gingerbread’, without carrier or manufacturer customizations. Google intended the Nexus line to exist as an example to Android manufacturers in hardware and software implementation. In what is now considered a failed experiment, the original Google phone was offered online-only through Google. The Nexus S launched with availability through carrier stores and other online retailers.