In Python 3 the built-in zip does the same job as itertools.izip in 2.X(returns an iterator instead of a list). The zip implementation is almost completely copy-pasted from the old izip, just with a few names changed and pickle support added.
Here is a benchmark between zip in Python 2 and 3 and izip in Python 2:
Python 2.7:
from timeit import timeit
print(timeit('list(izip(xrange(100), xrange(100)))',
             'from itertools import izip',
             number=500000))
print(timeit('zip(xrange(100), xrange(100))', number=500000))
Output:
1.9288790226
1.2828938961
Python 3:
from timeit import timeit
print(timeit('list(zip(range(100), range(100)))', number=500000))
Output:
1.7653984297066927
In this case since zip's arguments must support iteration you can not use 2 as its argument. So if you want to write 2 variable as a CSV row you can put them in a tuple or list:
writer.writerows((variable1,2))
Also from itertools you can import zip_longest as a more flexible function which you can use it on iterators with different size.