Phil Windley has notes on an interesting lecture by Alan Kay entitled Is the Best Way to Predict the Future to {Invent,Prevent} It?, which I stumbled on via the Torkington Radar:

Hurricane Katrina is Alan's new favorite story. When the city started flooding only four pumps kept pumping until the levee actually broke. The youngest pump that kept going was made in 1929. The newer pumps all stopped well before that. Try to imagine a computing system that will be working 90 years from now?

For some perspective on this, have a look at Sam Ruby's slides from his recent talk on "neurotransmitters", specifically about the technologies and companies that are less than ten years old today. Wifi. Instant messaging. Google. MapQuest. And so on.

Windley's synopsis of Kay continues (emphasis mine):

We live in the 80s extended into the 21st century. The only thing that's changed is the size. Windows XP has 70 million lines of code.... Microsoft engineers don't dare prune it because they don't know what it all does. Cathedrals have 1 millionth the mass of pyramids. The difference was the arch. Architecture demands arches.

The arch, apparently, was a significant innovation in building construction, because it serves to redirect tensile stress, which can be very hard on common building materials, into compressive stress, which is tends to work more with the existing compressive force of gravity. So, if building architecture demand arches, what kinds of analogous structures do other architectures demand? What is the arch in software architecture? What is the arch in architectures of participation?