A lot of hay made out of something that was on the car (and was known about) since October 2011 at the latest. It's an hydraulic interlinked suspension. Like what is on the McLaren MP4-12C roadcar, just without any computers changing it. It has been successfully tested at LeMans and there is at least one company selling such a system to the public. (And Mercedes buy the parts from Penske, IIRC.) Racecar Engineering had a feature on it but I don't remember the issue it was in.
Craigh Scarborough explains it better and in far more detail than I could:
http://scarbsf1.com/blog1/2011/10/17/mercedes-innovative-linked-rear-suspension/
Many, if not not most teams run a system like that. Mercedes' system is just better. And it was that great last year already, which is why they were fastest in Monaco, were (almost) only the mechanical handling of the car counts. Apparently Mercedes had issues with it last year, mainly because it was difficult to cope with changing temperatures, and thus they often ran with their tyres out of their operating window. But this was quite obviously rectified. (IIRC Lauda said a while ago that Aldo Costa simplified it and now it's perfect.)