I'm a complete coding noob (http://www.7bks.com/blog/179001) and along the way to learning programming have relied on StackOverflow for about 10 questions.
For every single one I have received complete, thorough, helpful and patient answers. In short, I could not be happier with SO. As a beginner it's been a phenomenal resource both for searching and for answering specific issues.
The post makes the point that newbies can't answer questions - and for me this is one of the reasons the quality of the site is so high. If you let anyone answer then you don't know how good quality the response is. As a beginner how am I to know if a given answer is correct?
Of course, any community site still has problems like this and SO is not immune to it but IMHO this is one of the ways they keep the quality bar higher than any other Q&A platform out there.