Sorry, Alex, I don't use Quicksilver. Lots of people do (by my count, maybe 50% or more of power users, as modeled by my colleagues). I'm sticking with Tiger's built in Spotlight capability. It's slower than Quicksilver, but it's built right into everything.
The uber-launcher turned master-controller that has Mac users raving. But can it act as my de facto universal tagging app? Do real people find it useful? Does Boris? del.icio.us/for/borismann: [from awsamuel] quicksilver: find not. do. or do not
And yes, not being able to add items/tasks/people to more than one category in OD4Contact *is* frustrating. I'm using project-based organization, since it is supposed to be mainly for task tracking, and this seems to work OK.