This means one XML sitemap will serve all three engines. All the small search spiders will quickly adopt, too.
Significance to retailers? Sitemaps provide a simple and consistent way to direct search spiders to all your pages. In some situations, creating this simple XML file can provide meaningful increases in organic search traffic.
Google's Grace Kwak writes:
If any website owners, tool writers, or webserver developers haven't gotten around to implementing Sitemaps yet, thinking this was just a crazy Google experiment, we hope this joint announcement shows that the industry is heading in this direction. The more Sitemaps eventually cover the entire web, the more we can revolutionize the way web crawlers interact with websites. In our view, the experiment is still underway.
If you are not providing an XML sitemap, do so. There's even more reason now. Check out sitemaps.org for more info. Easy, powerful, free.
Standards help us all.