This is great stuff!
Ran into a couple of problems on first run though.
In the input file, there's a double entry for the June Office Web Apps update, which causes the script to fail. Removing the second (looks like sharepoint) entry fixes it.
The initial media copy operations fail silently - can be worked around by copying manually
The extract operations fail - again, can be done manually.
I may be using some bad inputs, but as far as I can tell they're correct.