I suposse this is the output you need:
title,intro,tagline
2.9,Gardena,CA
It can be done with this changes to your code:
import csv
import itertools
with open('log.txt', 'r') as in_file:
lines = in_file.read().splitlines()
stripped = [line.replace(","," ").split() for line in lines]
grouped = itertools.izip(*[stripped]*1)
with open('log.csv', 'w') as out_file:
writer = csv.writer(out_file)
writer.writerow(('title', 'intro', 'tagline'))
for group in grouped:
writer.writerows(group)