From WhyDoPeopleMakeSoManyMistakes (and maybe other places):

''If builders built buildings like programmers wrote software, then the first woodpecker to come around would destroy civilization''

The woodpeckers are coming! DenialOfService attacks, CodeRedWorm, and so on, are making it harder to keep software running.
I'm sure there are other woodpeckers as well, such as constantly changing hardware, constantly changing requirements, the Y2K bug.
We have been able to handle some of these, and I claim we are learning how to handle more of them.
I claim software engineering is making some success in the face of the advancing woodpecker army. -- JohnFarrell

Aren't most of these woodpeckers hammering the same weak spots (buffer overflows and format string overflows)?  What we have is a lot of houses that are hard to upgrade. --PeteHardie

See also: ProgrammersBuildingBuildings