The average person likely won't even notice, but Webmasters can rejoice that Google, Yahoo, and Microsoft have banded together to support an unofficial standard for steering search engines in the right direction.
All three on Thursday announced they'd support a technique by which a little extra code in a Web page can indicate the address of its "canonical" version--essentially, the original, primary URL. The move will make it easier to tell search engines what they should pay attention to and to avoid treating duplicative Web pages as different.
Today, the search engine bots that scour the Web for pages to index don't have any particular way to know whether they should be pointing to a "http://www.somepage.com/index.html" or "http://www.somepage.com/index.html?lang=en"--the latter with an optional extra tidbit at the end that indicates the Web server should show the English-language version of a page. The new canonical tag can steer search engines toward the desired primary page, which in this example might ease browsing for non-English speakers.
In all likelihood, most people won't notice much of a difference. Perhaps that the URLs in search results on which they click will be a bit shorter, and perhaps that search engines won't be cluttered with repeats of the same pages in search results.
But the bigger benefits are for Web site operators, which can ensure a more consistent experience for people using their sites and cleaner data collected about how people use their sites, and for the search engines themselves, which won't have to make as many guesses about the pecking order of similar pages.
Also notable is that Microsoft, Google, and Yahoo are cooperating. Standards aren't always easy to hammer out, even informal ones such as this. Supporting canonical tags, though, probably won't mean give any search engine any new advantage or disadvantage, so this was probably relatively easy to create.
Now if the companies could only join forces better on e-mail identity authentication and instant-message interoperability, the world would actually look better for the average person, too.