[armitron]

Not at all, SMP opens a huge can of worms both for userland and kernel security. Suddenly you have all sorts of weird race conditions to deal with and in some kernels (cough XNU) logic bugs that stem directly from how kernel subsystems interact with threads. I don't blame OpenBSD for not going down that route.

[cm3]

Which is why DragonflyBSD was forked during the disagreement on FreeBSD's SMPng. Matt implemented more of a message passing system instead and Sepherosa Ziehau made all kinds of improvements to share as little as possible between cores and thus enable higher scalability in particular for networking.