In a small bowl, cover the currants with hot water and let stand until softened, about 10 minutes. Drain.
In a large nonreactive bowl, combine 2 tablespoons of the olive oil with the garlic, cumin, lemon zest, half of the lemon juice, 1/2 teaspoon of salt and 1/4 teaspoon of pepper. Add the zucchini and currants and toss to coat. Let stand at room temperature for 2 hours, stirring occasionally.
Meanwhile, in a large, shallow glass or ceramic dish, combine the minced shallot with 2 tablespoons of the olive oil and the remaining lemon juice. Add the chicken breast halves, turning to coat thoroughly with the marinade. Cover and refrigerate for 1 hour, turning a few times.
In a small skillet, toast the pine nuts over moderate heat, tossing a few times, until golden brown, about 2 minutes. Transfer to a plate and let cool.
Remove the chicken breast halves from the marinade, scraping off the shallot. Slice the chicken on the bias 1 1/2 inches thick and season with salt and pepper. In a large skillet, heat the remaining 2 tablespoons of olive oil. Add the chicken slices and cook over moderately high heat, turning a few times, until lightly browned and cooked through, about 8 minutes.
Transfer the chicken to a large, shallow serving bowl and let cool slightly. Add the marinated zucchini and currants, toasted pine nuts, arugula and preserved lemon and toss lightly. Serve right away.