Sepherosa Ziehau posted an extended description of his work with nginx on DragonFly, and the kind of performance he was able to wring out of it.  Of special note: he posts all his sysctl changes, which might be useful to anyone else in high-traffic environments, and notes that he was able to saturate a 10Gb link with one DragonFly machine.

Also: a followup comparing interrupt vs. polling performance.