It's not so surprising though - it just means that the ants have been able to spread faster than their rate of evolution/mutation. Otherwise, they would have differentiated/speciated first. But because it's so easy for them to hitch rides on passing people, cars, boats, and airplanes, they've spread a lot faster than they would naturally have been able to.
The more interesting thing will be to observe over time and see how long it takes before their super-colony collapses or is torn apart by civil war. Of course that's not likely to occur until their paths of transport and communication are disrupted. If we don't destroy ourselves first, thus giving them a long time to continue to evolve in total connectedness, I guess things will get interesting for them down the road...
The other interesting point this raises is about language and communication in general - biologists frequently talk about animals communicating with each other via whatever their particular mechanisms may be, but they seem to assume that all the members of a species are homogeneous in their communication methods. That's a pretty naive assumption, given all the different vocal and non-vocal mechanisms various human tribes use to communicate. The interesting question here will be whether this super-colony is an example of genocide (the total annihilation of different/competing ant species) or assimilation...