Google's smart snippets include some useful information: the number of answers, the date of the most recent answers. Not all question answering sites show the status of a question, but Google is able to detect solved questions.
Depending on your query, you might want to read a brief answer or a detailed response. Google lets you find web pages that include short, medium or long answers.
You can try this feature by changing your Google cookie. Go to google.com and paste this in the address bar:
If you're not in the US and Google redirects you to a different domain, replace google.com with the appropriate domain.