Here's a really dumb python script that prunes the livecd-creator cache directory - or, any directory with a big lump of RPM files in it, really. It finds (roughly, but we're not going for the World Accuracy Prize here) multiple versions of the same package and removes all but the newest one (it relies on ls to order the files by date after ordering them by name, which it does here, but YMMV). Run it from the directory you want to prune. No guarantees given at all, may eat your babies.

#!/bin/python

from subprocess import check_output
import re
import os

sep = re.compile('-\d')

output = check_output('ls *x86_64.rpm', shell=True)
lastfile = ''
for rpmfile in output.split('\n'):
    if sep.split(rpmfile)[0] == sep.split(lastfile)[0]:
        os.remove(lastfile)
    lastfile = rpmfile

output = check_output('ls *noarch.rpm', shell=True)
lastfile = ''
for rpmfile in output.split('\n'):
    if sep.split(rpmfile)[0] == sep.split(lastfile)[0]:
        os.remove(lastfile)
    lastfile = rpmfile

output = check_output('ls *i686.rpm', shell=True)
lastfile = ''
for rpmfile in output.split('\n'):
    if sep.split(rpmfile)[0] == sep.split(lastfile)[0]:
        os.remove(lastfile)
    lastfile = rpmfile