It is 2012 Jan 28 and I have just now encountered some relatively recent reports on trans-Atlantic fiber optic capacity. It quotes about 4*1013 bits/sec total. The cost of laying the physical cables was largely written off as a total loss due to excess fiber, and the current transmission prices largely reflect the incremental cost of the equipment to insert bits into the fiber at one end plus that to extract them at the other. The bandwidth per fiber is growing as demand increases and technology improves. It is not near theoretical bandwidth because: The reports suggest that more fiber may be built in a few years, but only if the price, due to new demand, warrants it.

A new TA cable was recently laid not for capacity but for low latency.

2009 Atlantic, too; Submarine Cable Map; Ocean Cable Map