Stack Overflow is already more than 2 years old, and I still find people with high reputation answering to my questions with a plain Wikipedia link or a "do a google search". I may condone it for newcomers or new beta Stack Exchange sites with different, younger communities, but I find it unacceptable especially after it has been a topic for ages.
When you find such an answer, flag it for moderator attention and mark it as "not an answer". If people feel that the only information they can add to the topic is a link to google, wikipedia, or some other site, with no other commentary or excerpt, then it should be posted as a comment, as it's not an answer.
Stack Overflow should be the resource other people are linking to, not simply a list of links to other resources.
If you come across a question which a simple google search will answer, do the google search, then summarize what you find with a few relevant links in your post.
But there's no need to post an answer with a single line of text or less that essentially tells someone to go somewhere else for their answer.
The policy about "google it" might change slightly. There's suggestions that if it's trivally easy to answer, then it may be closed as "General reference". Stack Exchange blog: Are Some Questions Too Simple?
I think the specific question Stefano cited
is a perfectly reasonable question that indicates prior research and asking why. Feel free to cite https://stackoverflow.com/faq where it says
If your motivation is “I would like others to explain ______ to me”, then you are probably OK