from socket import *
import sys

if len(sys.argv) == 1:
    print "Uso: prueba_comp http://sitio.com/pagina.html"
    sys.exit(0)

surl = filter(None, sys.argv[1].replace("http:", "").split("/"))
surl.append("")
sock = socket(AF_INET, SOCK_STREAM)
sock.connect((surl[0], 80))

sock.send(
    'GET /%s HTTP/1.1\nHost: %s\nAccept-Encoding: gzip\n\n' %
        (reduce(lambda x, y: x+"/"+y, surl[1:]), surl[0]))
data = sock.recv(1024)
sock.close()

if data.find("Content-Encoding: gzip") != -1:
    print "Ok. Comprimido"
else:
    print "Fallo. No comprimido"

$ prueba_comp http://libertonia.escomposlinux.org
$ prueba_comp http://www.kuro5hin.org