Authority Evaluation Lost - The Changing Backlinks Command
The first change is with Yahoo, where the link: command cannot be issued without the full URL. For example, 'link:http://www.website.com' will work, while 'link:www.website.com' will not.
The second and more important change occurs in Google. The 'link:' command in Google, as of Summer 2004, only displays a random selection of backlinks, rather than a full listing of higher PageRank (PR) backlinks. This continues Google's downward trend of showing an ever decreasing number of incoming links to a webpage.
To compare this to Google's past use of the 'link:' command, prior to this past summer all backlinks were listed when they maintained a PageRank of 4 or above. This measure may not have been comprehensive, but gave a good sample of authoritative sites linking in.
So you ask, why is the backlinks command important to Librarians? The answer is that backlinks offer a window into the concept of link popularity, which is a critical component to most modern search algorithms. But more importantly for Librarians and other sophisticated search users, backlinks are used to evaluate a website's authority and whether it can or should be considered a trusted source.
Why would Google do this? To put it simply, Webmasters have abused this window into their search algorithm. By knowing the backlinks of high ranking websites, webmasters have attempted to duplicate the efforts of others in the race to the top of the SERPS (Search Engine Results Pages) for profitable keyword combinations. Not an unreasonable response from Google, but that's not going to help us.
Now that the backlink window is closing shut, Librarians will have to use Yahoo to gage a website's link popularity. For now it's the more comprehensive tool. But also be forewarned, I believe that reviewing a site's backlinks as a measure of authority will likely be a lost tool for Librarians in less than two years.