I am getting this exact same error: Warning! Domain mapping upgrade for this domain not found. Please log in and go to the Domains Upgrades page of your blog to use this domain.
Did this get resolved once your nameservers fully propogated? I changed them yesterday afternoon. I have twenty70hosting and I have been working with tech support all day. She can go to my site lifeencouraged.com and see my new wordpress.org account but I get the above error message when I try to go there.
Any help would be greatly appreciated.