Webmasters are becoming increasingly aware of the power of the sitemap as an SEO tool, enabling search spiders to crawl more pages in less time with the end result of getting more or your links indexed faster. Because sitemaps require only those pages that have changes to be visited, valuable bandwidth can also be conserved.
The news that Google, Microsoft and Yahoo! have all finally agreed to support the single Sitemaps 0.90 protocol will only make this process ever easier. Given that, according to most sources, the big three have around 85% of the search engine market share, this announcement should not be undervalued. And by support, of course, they mean not only use sitemaps but also help with a joint development program. Think of it as being an open standard for SEO and you are not far off the mark.