More traditional Python:

  >>> import operator
  >>> a, b = [1, 2, 3], [4, 5, 6]
  >>> map(operator.add, a, b)
  [5, 7, 9]

List comprehensions are a relatively late addition to the language and don't really warrant being called "more Pythonic" in this case IMO.

(Yet more traditional Python would be the plain for loop, of course)