Though there are still a few wiki pages that haven't been cleaned up, spam hasn't been issue on Trac for awhile now.
With respect, albert, I've just been through all the pages in the TitleIndex on the Trac wiki. There were only four that didn't have any visible spam (TracGuide, WikiNewPage, WikiStart and the TitleIndex itself); the others seem to be a roughly even split between "original content with a couple of pages of spam tacked on the end" and "page content deleted, replaced by spam".
That said, I didn't see any edits newer than 11 months, so I agree that it's not an ongoing problem. Saying that "a few" pages still need to be cleaned up is rather understating things, though.