I was in the Borders on Oxford Street today. Out of curiosity, I looked in the Computing section - it didn't help that it was abysmally organized, but I couldn't see a single Perl book. Not one. Zilch. I remember looking in Foyles a little while before that, and finding maybe two Perl books. Yes, two - and one of them was the one with the monkey on the front. I had a similar result at a Waterstone's somewhere (I forget which), and wouldn't be surprised if Blackwell's don't have any either.