There's a good argument that the two relevant mindsets in today's internet world are "cellhead" and "nethead."  Cellheads are happy with walled garden mobile networks, in which all services are approved, all devices are authorized, and spam isn't a problem.

Netheads, by contrast, are looking for open, public networks of user-generated (or at least -commented upon) content and metainformation, in which applications don't have to be approved and to which any device can attach if it knows the protocol.

IMS/NGN represents the standardization of the cellhead mindset and the suggestion that it will enter into the nethead world.  We need empirical evidence that cellhead approaches lead to less dynamic growth -- the mobile world is certainly growing quickly, but arguably won't provide as rich and interesting a future as the nethead network.  Back to layers again:  emergence and metainformational growth depend on the existence of independent layers that allow experimentation and mistakes.

On the other hand, as Martin Geddes says, asking for all  networks to be "neutral" networks (in which layer independence and nondiscrimination are mandated) can be extraordinarily pernicious.  We should only do it in markets for internet access that are clearly broken because they are dominated by one or two players -- where a choice of plain vanilla access just isn't available.  That appears to be the situation in the US generally (albeit not, perhaps, in San Francisco).

So let some network providers go into the IMS/NGN world (which will foster more ads like this one, asking you to tell your broadband provider to let you have a particular service).  As long as there are choices, we'll be fine.  If there aren't choices, we'll need to mandate nondiscrimination.  But it won't be easy.

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Planes are the new libraries.  On my way back to NY yesterday, a woman in front of me opened up her laptop and started watching a 1930s American musical with subtitles.  It was loud.  The people around me stirred uncomfortably.  They were all reading -- books, Bibles, magazines.  The man next to the laptop-lady removed the headphones from his ears and offered them to her, showing her where they could attach to her computer.  He then took out from his bag an extra pair for himself.  Planes are the places to read these days, and we all settled down again for a few more hours of quiet.