A few months ago, I wrote Ruby Book Sales Pass Python. Well, in his talk at OSCON on Friday, Roger Magoulas, the director of O'Reilly Research, revealed that they've now passed sales for Perl books as well. Here's his graph (click on it to pop up a larger image): As described in my posting Book Sales as a Technology Trend Indicator, data is from Nielsen Bookscan's point of sale reporting on sell-t