"As of Friday, December 14, Xbox customer support will no longer manually migrate an Xbox Live account from one region to another," Microsoft informed us this afternoon. "The conclusion of this pilot program is in preparation for the release of an automated tool which will be available in mid-January on Xbox.com."
One significant caveat for travelers is that region switching can only be done once every three months. This may be a problem for those who wander the world on business, but if you're swapping between the summer home in the Hamptons and the chateau in Chamonix, you'll be all set.
Other provisos: some services are region locked, like IPTV, Xbox Music Subscriptions, along with the Hulu and Netflix.