Some of this depends on how much you are willing to pay. The issue is as much 10G orders at today's transit prices as it is the capacity. We're used to paying less per unit for greater capacity, but when we're asking networks to sell capacity in chunks as large as the ones they use to build their backbones, that may simply not work. 

One other issue is that willingness to sell 10G is one vital competitive distinguisher in an otherwise largely commodity transit market. There have been rumors that older legacy carriers wish to punish more agile competitors for daring to "steal" 10G customers away from them, in spite of the fact that those older carriers have lots of trouble delivering 10G.

- Dan