I was getting a weird "RED X", when trying to add my sitemap.xml for DevHub domains on Google WebMasterTools.
The problems is that you need the www on the domain when you add it to WebMasterTools, like: "www.VerrucaVulgaris.com".
This is because DevHub puts the www in the sitemap.xml, which google doesn't like unless the domain exactly matches.
I had to figure it out on because I can't stand GetSatisfaction -- the tech support pages on DevHub.com. Too painful/hard to use.
Happy Domain Hunting!