Sure it can - but not using copper, it needs the fiber based implementation*
And - lo and behold - the Apple gear with TB ports are optical ready ... http://www.tuaw.com/2012/03/13/optical-cables-for-thunderbolt-coming-in-2012/
But thats irrelevant. The iMac is an All-in-one device. The display is not connected by a TB port, it is wired into the mobo. For everyone else ... wait for the upgrade to fibre TB cable later this year.
* I am trying to find the link that showed the speed of the fibre vs copper TB, but can now only find info suggesting that fibre will allow greater cable runs.
Fiber in and of itself only offers the possibility of faster speeds, it doesn't speed up the port on its own! The electronics has to be fast enough to offer up that additional speed and it would need a way of knowing that the optical cable is attached. From what I can see all references to optical cables for today's TB ports indicte their primary advantage is long distance connections.
So we would need TB 2 to drive those high resolution displays. Or another solution, that works in conjunction with the limited bandwidth. There are more thana couple of possible solutions to that bandwidth problem.