It's something she learned from Stick and the Chaste in Elektra: Assassin. She briefly uses it to communicate with Wolverine in Wolverine: Enemy of the State. Though I'm not sure she can read minds as much as she can simply 'speak' to others' minds. It's been a while, but in W:EotS it doesn't seem like she can hear Wolverine 'talking' back to her.
And don't forget her Dark Reign mini where we see her able to lock/unlock specific memories from her concious mind.