I think the biggest problem is the mods don't have the power (as far as I know) to outright ban people, although they can suggest this to David.
everybody has a life outside of internet forums, so expecting threads to be locked down straight away is a little un-realistic.
perhaps the easiest option would be to take note of the spamming addresses and add them to the language filter, thus making the spammers look more like the computer t**ts they are. when their link is replaced by a link to something else.
(perhaps shop.apple.com would be a good redirect for the freeipod links)