Several of my colleagues and I have recently upgraded from MySQL 5.5 to MySQL 5.6 using homebrew on our Macs to test locally before upgrading our servers. Since this upgrad
I struck this problem with mysql 5.6.16, freshly installed via Homebrew on Mavericks, along with rbenv and rails etc.
Decided to reboot before working through the other solutions here. Problem solved!
So if you haven't rebooted since installing mysql etc, I'd recommend restarting before working through the answers here.