Serial number-based piracy protection was a "feature" of iWork when it was introduced in January 2005 as iWork '05 and has remained an iWork-installation requirement though its '06 and '08 incarnations.
And now it's gone.
We asked Apple the reasoning behind their decision to better enable iWork piracy, but at press time, we had not yet received a response.
So let's guess.
First, the basics: While iWork has its fans - especially those of its fluid and powerful presentation software, Keynote - it's far from being a dangerous competitor to Microsoft Office for Mac 2008.
And Apple is now preparing to launch a pay-to-play version 1.0 of its iWork.com online document sharing, reviewing, and commenting service, which is now in beta. iWork.com requires iWork '09.
Removing piracy protection can increase the installed base of a product. And when that product is not an industry standard such as Microsoft Office, it's a safe bet that piracy will be limited to an extra installation or three for some relatively small percentage of legal copies. It's unlikely that child laborers in some Southeast Asian sweatshop are going to be burning millions of copies of iWork '09.
For iWork.com to become a money-maker, a large installed based of iWork '09 users needs to exist. And since iWork.com will almost certainly be a subscription-based service - a service that generates a steady stream of regular payments - it just might make financial sense for Apple to passively encourage "extra" installations of iWork '09.
After all, it's not as if Cupertino is losing $79 for every pirated installation - pirates often "repurpose" software they wouldn't have bought otherwise.
Our cynical self can't suppress the idea of other possible development: If the removal of iWork '09's serial-number requirement does, indeed, increase the productivity suite's installed base, and if a significant portion of that installed based gets hooked on iWork.com, and if a future version of iWork requires that users upgrade to that new version to be able to continue to use iWork.com, then Apple might choose to reapply the serial-number requirement for, say, iWork '10.
Cynical, yes - but possible. ®