When you say unlock, do you mean the multiplier or the extra cores? If it's the multiplier, any of the AMD CPUs labled as Black Edition already have the multiplier unlocked. All the others have the multiplier locked which means you cannot increase the multiplier to overclock and there is no way to unlock them.
If you mean getting extra cores, any X2 or X3 processor has locked cores that can potentially be unlocked, but it's a crap shoot as to whether or not you will be successful with it. Also, you must have a motherboard that has an ACC option. Setting this is to enabled or hybrid (depending on the board you have) will unlock the cores, but at that point, it's hit or miss if it will be successful.