Well, finally got around to implementing a CAPTCHA control in my comments (using the excellent HIPValidator by Stephen Toub). It's still experimental - so it might not work totally smoothly - but let's see if it works against comment spam! Anyway, any problems please email me at blogcomments@mostllyucid.co.uk . Oh, should say I won't be able to provide the source for this (most of it is in the article I mentioned above) because my .TEXT source is heavily modified...
UPDATE: Looks like there's an issue around a font installed on my server - this causes the little image to not appear, just hit refresh until it does, I'll fix this later tonight.