"Because we don't know how to make a wheel that is still generally useful for legitimate wheel applications but useless to bad guys."
Cory Doctorow's 28C3 talk The Coming War on General Purpose Computation (abstract, transcript) warns that "the coming century will be dominated by war against the general purpose computer, and the stakes are the freedom, fortune and privacy of the entire human race." [more inside]
The holiday season isn't always relaxing for those in the computing security field. 2011's Chaos Communication Congress brought many gifts in the form of vulnerability disclosures, including: malicious documents that infect HP printers, remote control vulnerabilities in prison lock systems, and denial-of-service attacks against Web servers written in just about every scripting language.