This answer on meta.SE is quite informative about how the protection system works in general.
On this site, only moderators and users with 3,500+ reputation can protect a question.
For the uninitiated: "protecting" a question means that only users with more than 10 reputation can answer it. Protection is designed to prevent new people (who don't understand the norms of stack exchange) from adding low-quality or spurious answers to high-visibility questions they have stumbled upon.
For now, if you see something you think you needs protecting (i.e. a question that is attracting spurious answers from low-rep users) then my suggestion would be that you flag it for moderator attention and we can protect it. The same goes for a protected question where the protection is no longer needed and which should therefore be unprotected.
The guidelines on protection say the following:
Do protect questions that are attracting a lot of non-answers or very poor answers (spam, etc.) from new users.
Don't protect questions just because they're linked to on a high-traffic news site like Reddit or Ars Technica. While there's certainly some correlation between sudden spikes in popularity and associated non-answers, not all popular questions suffer from this.
Do unprotect questions that aren't currently attracting a lot of attention and don't have a long history of unproductive answers.