Interesting, thanks. I'm actually surprised that Baidu ranks as low as it does, given its overwhelming market share in China and the fact that most code out there is in English. I just did a quick experiment and googled some common errors, then compared the SERPs to those of Baidu. SO was ranked similarly in both. Do Chinese programmers not goog...er, baidu errors?

Actually, that leads me to a more relevant question: looking through the queries that landed visitors at SO, have you done some scraping to determine what proportion were people googling errors verbatim, and what percentage were people asking questions or googling a particular topic, eg "scaling rails"?