I'm quite surprised nobody's commented on this yet!

Not only is there a whole new section of the TfL site devoted to it
(http://tinyurl.com/5euecn), they've even produced detailed
specifications for the 'serious' competition in proper house style.
These look very businesslike and impressive, with the occasional bit
of humour (Articulated design: No. Doors/Apertures: 1 open platform at
nearside). It's at http://tinyurl.com/6gnvpt if anyone's interested.

I know Autocar magazine sponsored a design company (Capoco?) to come
up with a New Routemaster concept a while back - I wonder if they will
enter it. Otherwise, I can't see any of the bus builders taking this
as anything other than the humorous whim of a bored politician...