Techcrunch reports:
In an encouraging act of collaboration, Google, Yahoo and Microsoft announced tonight that they will all begin using the same Sitemaps protocol to index sites around the web. Now based at Sitemaps.org, the system instructs web masters on how to install an XML file on their servers that all three engines can use to track updates to pages. This should make it easier to get your pages indexed in a simple and standardized way. People who use Google Sitemaps don’t need to change anything, those maps will now be indexed by Yahoo and Microsoft.
I.e. it looks like they all agreed on Google's defacto standard?