Phil comments on Brasilia and the end of oil, and speculates (along with the article he links to) on what will become of our "traditional" population distribution.
This is good stuff to keep in mind when talking about local (i.e. urban/suburban) infrastructure - trains, park n ride, etc. Consider too, for instance, the current trend for out-of-town shopping centres, supermarkets and IKEAs that rely on the availability of car drivers.
The UK government also seems committed to expanding air travel, preferably via an "emissions trading" scheme so that countries can buy the ability to pollute off other countries. It remains to be seen whether this would actually lead to more efficient technology, or just price-influencing tactics or political "persuasioning", in a time when a country's economy depends more and more on oil, and when there's less and less of it around.
In other words, we don't seem to be set up in any way (at least not mentally or emotionally) to face a rapid rise in fuel prices. Our "solutions" seem to be concentrated purely on the technical aspect - i.e. alternative energy - rather than looking at the way in which our society works - a society based on free movement, which in turn is based on cheap and readily-availble fuel (a catch 22 there?). At some point, we're going to have to start making big sacrifices to what we know.
Which brings me to Phil's question: "shouldn't I be doing something to plan for the end of cheap oil?"
There are things we can and things we can't do - or rather, things that will make a difference and things that won't. IMHO, encouraging less dependency on energy is a hundred times more important than working out new power sources. wu-wei in t'ai ch'i is (roughly :) the idea of using as little of our own energy as possible to achieve the greatest effect - often relying instead on energy coming from the thing we want to affect. In other words, it can be considered that there is a "natural" flow to any system, and the most efficient way of "powering" the system is then to attune to that naturalness.
What do we have today? A focus on producing "things" just for the sake of their production - economies to justify themselves, rather than to justify living itself. In many senses, this is extraneous expenditure of energy, just because to reduce usage would be somehow "backwards". And all this on a foundation of inefficient fossil fuels and yang.
Nothing is sustainable really, it's just a case of how long we stretch things out for. At the current rate, maybe another 100 years is my guess. Things'll get really bloody then.