The mystery has been relealed - the php|architect folks have posted about their secret today - a discount on single issues of 30%.

Seasons greetings everyone! The first of two surprises from us today is a great opportunity to combine our recent drop of all DRM protection on our PDFs with an awesome 30% discount on our single-issue prices to stock up on all your favourite past issues of php|architect.

This means that single issues are priced at (about) $3.49 CAD for a few days - all you need to do is pick your favorites from their archive, even their most recent issue.