Aaagh, super-weird spam

OK, so my new entries on this blog are showing up in Google Reader with the correct titles, but with the following body text:

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…which is Bad, and implies Evil People have hacked the site. But I’ve checked all three feeds (I’m using the one at /feed, RSS fans), and all the files are clean.

So:
a) is anyone else seeing the spammy nonsense?
b) what the hell is going on?

Update: thanks Unity. I’ve temporarily solved things (although I haven’t done the detailed clear-out of database tables that’s also required, gulp. TOMORROW). Whilst doing so I’ve accidentally deleted the main theme. I could restore it, but it wasn’t widget-compatible anyway and at least now I’ve got a project for my non-drinking, constructive weekend….