According to Gavin:
Tablet PC: The InkAnalysis API has RTM’d and the download is LIVE!
"new InkAnalysis API which integrates layout analysis with handwriting recognition (and exposes new capabilities and features). So far, I’ve pointed developers to the “Windows Vista SDK for RC1” to install the InkAnalysis API. I’m very excited to announce that the InkAnalysis API has now RTM’d and can be installed via the new addendum to the last Tablet PC Platform SDK (1.7). This new release is called the “Input Supplement” and its version is 1.7.5."