I saw this password strength post on XKCD, which was posted on 10th August 2011.
There is all kinds of debate about how secure this method of generating passwords is, but I wanted to have a play with the method anyway. I think the advice in XKCD is still valid, from what I have read online. However, doubtless lots of people could find evidence to the contrary.
There's a lengthy piece about the XKCD approach via explainxkcd.com.