Okay, simple question: How long does it really take you guys to restart Steam?
Simple question, but completely irrelevant. If I didn't check Blue's News, I'd never know when a new game type or patch was released because I let Steam run all the time and rarely reboot. I've never had Steam tell me about an update (or even that Half-Life 2 was available when it came out) without me restarting it, which is annoying. It's like Valve designed Steam as an app you can just keep running, but then completely removed the functionality that makes running the app continuously worthwhile.
To answer your question though, it takes 2 seconds once I find out about the update.