This sorry state of affairs is my fault. I have allowed comments without moderation because I would rather zap the occasional spam than moderate all the comments. But, until Joel Garry alerted me, I had failed to notice that spamtards were spamming old posts. As Joel said, some of the stuff was nasty, really explicit pr0n sites. So, moderation for older posts is now in effect - it's already caught a couple.
In the meantime I have a large housekeeping task. One post - on multi-core licensing, bizarrely - has over 150 spam comments, and as I have already said, "Jerry" has spammed every single post. It is unfortunate that Blogger does not provide the functionality to delete comments in bulk, despite being desired for several years. So the only option is to delete each spam comment individually, which as Bill Scott has observed, is a rather user hostile design.
The question behind all this is why Blogger doesn't provide the functionality. It's not like it would be hard to offer a list of all the comments with a check box and a Delete All button. The Google forums (they own Blogger) have lots of questions but no useful advice. It is especially puzzling when compared to the excellent way GoogleMail handles spam.
Now I am off to zap a few more comments. With a song in my heart and a smile on my face, naturally.
Update: 19-JUL-2009
Unfortunately my prediction was wrong and "Jerry" didn't post a spam comment to this thread. However, the moderation filter picked up another spamtard trying to post to this thread. The text is so wildly inappropriate that I was almost tempted to publish it:
I'm glad you're back to posting. I love reading about your shopping adventures and great finds. Your outfits are always super cute too!Thank you, "Julia", your outfits are always super cute too.