OK, so it turns out that it was my Linksys WRT310nV2 router all along. Not really sure why, but it was preventing my Buffalo Linkstation LS-XHL from performing DNS resolutions, and Akismet was therefore unable to consult with the mothership.
I upgraded the Cisco (Linksys) WRT310n to the DD-WRT, which I’d been meaning to do for a long time anyway, and the problem is magically solved.

DD-WRT is pretty damn amazing, really. With this free, open-source, upgrade, the Linksys is now much more capable and with a more powerful and modern web interface.
Strange that the commercial administrative interface was so poor in comparison.

Is it me or is my web site faster? Could the default router image on the WRT310n really have nerfed my entire operation?

WHAT? And now the BitTorrent engine in the Linkstation is functioning? Really, I just assumed it was broke for reasons of being crap; apparently it was the router all along. So my Buffalo can obtain on my behalf now. GO FORTH AND GET ME THINGS!

Anyway, with Akismet back in charge of moderating my comments, I’ve turned the comment feature back on. All two of you who are likely to post such a thing may do so now.