No the 3820 isn't unlocked, you can still overclock it though but I don't think it has an unlocked multiplier. The only unlocked processors on the 2011 socket are the 3930K and the 3960X.
Edit: Some internet searching will help you to find a more in depth explanation of the overclocking potential of the 3820. I have seen reviews where they take it to around 4.7ghz