Ink Services update? What does it mean?

Some of us know that Apple has had what it calls "Ink Services" for the Macintosh since 10.2 at least. Ink Services is handwriting recognition for graphics tablet users. Now, Apple announced today that they've updated the documentation to provide an API for customization. This is their first documentation change in almost 3 years. Why the sudden interest? Is a tablet Mac on the horizon?