Yahoo! has now given its nod to accept Sitemap protocol. The sites can be now authenticated through Yahoo! Site Explorer. But to get your site authenticated by Yahoo! you are required to first make an authentication key file and then upload at your site's root. After uploading you can request Yahoo! for authentication and you will get the answer in 24 hours. But at the same it is very important to note that you do not remove the authentication key once Yahoo! has authenticated your site. This is because Yahoo! from time to time looks for existence of the key and on its removal the site can be unauthenticated.