Rinse scallops gently under cold water; drain. If large, cut in half.
In hot butter in large, heavy skillet, saute shallot 2 minutes. Add scallops in a single layer (do half at a time, if necessary). Saute over medium heat, stirring occasionally, until browned and cooked through - 5-8 minutes.
With slotted spoon, remove to heated platter; keep warm.
Add vermouth and parsley to skillet; cook over low heat, stirring to dissolve browned bits, until bubbling - about 1 minute. Pour sauce over the scallops.
Garnish scallops with lemon wedges and additional parsley, if desired.