Earlier quoted context omitted.
No, we don't. I don't want some guild or certification authority telling me I can't program for a living until I've done 2 years of "journeyman" programming and passed my licensing exams.
I'm having trouble finding it right now, but there was a good argument posted here a while back for requiring a certification proving that programmers know how to write secure code. The analogy was that the market can already sort out good chefs from bad chefs, but that there should be a basic certification to prove that you understand food safety.
If we had mandatory security certifications, Reddit wouldn't exist. Nor, for that matter, would Windows. And while many of us would probably rejoice at that, I think a lot of people would be pretty pissed off if they had to use OpenBSD.
BTW, I interned at a company that does avionics/medical devices/financial software. Those industries do have strong regulations, like mandatory code reviews and traceability matrices. And that's great for what they do, but I'd hate to see the same standards applied to your Web 2.0 social bookmarking site.