Printing out JSON data from Twitter as a CSV
Put all import statements at the top.
You might leak a file descriptor, since you call open(sys.argv[1]) without closing it.  (Whether a leak actually occurs depends on the garbage collector of your Python implementation.)  Best practice is to use a with block, which automatically closes the resources when it terminates.

with open(sys.argv[1]) as in_file, \
     open(sys.argv[2]) as out_file:
    …

It would be better to define your variables in the same order as they will appear in the CSV output.
Rather than creating an empty array and appending to it in a loop, use a list comprehension.

tweets = [json.loads(line) for line in in_file]

You read all the tweets into an array of JSON objects, then slice the data "vertically" by attribute, then re-aggregate the data "horizontally".  That's inefficient in terms of memory usage as well as cache locality.
Unless you have a good reason, just transform one line of input at a time.  (A good reason might be that you want to produce no output file at all if an error occurs while processing any line.)




import json
import sys
from csv import writer

with open(sys.argv[1]) as in_file, \
     open(sys.argv[2], 'w') as out_file:
    print &gt;&gt; out_file, 'tweet_id, tweet_time, tweet_author, tweet_author_id,    tweet_language, tweet_geo, tweet_text'
    csv = writer(out_file)
    tweet_count = 0

    for line in in_file:
        tweet_count += 1
        tweet = json.loads(line)

        # Pull out various data from the tweets
        row = (
            tweet['id'],                    # tweet_id
            tweet['created_at'],            # tweet_time
            tweet['user']['screen_name'],   # tweet_author
            tweet['user']['id_str'],        # tweet_authod_id
            tweet['lang'],                  # tweet_language
            tweet['geo'],                   # tweet_geo
            tweet['text']                   # tweet_text
        )
        values = [(value.encode('utf8') if hasattr(value, 'encode') else value) for value in row]
        csv.writerow(values)

# print the name of the file and number of tweets imported
print "File Imported:", str(sys.argv[1])
print "# Tweets Imported:", tweet_count
print "File Exported:", str(sys.argv[2])