Large, showy purple spikes -- an escaped ornamental. I was slightly bummed because I thought I missed getting a shot of this this spring, but discovered one stashed away.
Had this mis-IDed for years as Dame's Rocket (Hesperis matronalis), but the leaf shape (frankly heart-shaped) is consistent instead with Honesty, and the veining of the petals looks closer too. Honesty isn't shown by PLANTS as naturalized in NJ, but it is shown in eastern PA.
EDIT: Now (2015) showing in PLANTS as naturalized in this county (Middlesex).