There was a very good article in the MX5 magazine (called Soft Top Hard Top) which explained the new tests introduced during 2012. The areas covered are as follows :-
Steering and Suspension
Tyres and Road Wheels
Seat Belts and Supplementary Restraint Systems
Body, Structure and General Items.
I am not sure if everybody is aware of the changes but it certainly makes the MOT considerably more complicated and will probably catch a few people out.