I can’t help it; I’m still calling Google Webmaster Central "Google Sitemaps". What can I say? It’s more defining of the function to me. Webmaster Central theoretically encompasses a broader set of functions than just the Sitemaps – however, most of the issues I ever address have more to do the Sitemap functionality.
However, that’s off the topic for this post. What I actually intend to write about it Google’s recent changes to the preferred domain feature in Sitemaps. Previously, they automatically added the "non-preferred" domain to your listing of sites owned when you set a preference. They will no longer be doing this, do to complaints of confusion from users.
I don’t know how widespread these complaints were, but it certainly came up in a Cre8asiteForums thread in August, where Vanessa Fox actually responded to a member’s complaints about the preferred domain system.
It’s nice seeing Google explicitly responding to problems – and in a reasonably efficient manner, as well. The complaints were initially posted on August 20th at Cre8asite, and the changes were announced today – September 12th. Three weeks isn’t a bad turnaround.
That said, it’s important to keep in mind that your www and non-www versions of a domain are, technically speaking, different web addresses. Like any subdomain, the "www" domain represents a subset of what can be present on your domain name. Although having this automatically added is confusing, given that many people don’t differentiate between the two addresses, maintaining the ability to register separate Sitemaps will still be possible.