Will the latest 346 (G-VFIZ) have the new logo or the old one?
Seems unlikely:
http://www.airliners.net/open.file/1064957/L/
The tail is already done in the classic Virgin "scrawl" with purple edging.
The tail, sometimes just the rudder, is usually already painted when it's attached to the aircraft to help with balancing the aircraft during construction. In the case of the Airbuses, it's also because the tail is made of composites, so it's painted before it leaves the factory.
Obviously, this one was already far enough along before the new paint specs were available.
Cheers,
Mike