10.4.2 mentioned on an AppleScript page
While the update's still missing from Software Update,
this page about Standard Additions to AppleScript mentions the upcoming update. So here's to the hope this means it'll be released soon. The latest build (8C44) feels very stable indeed, ready for production, our sources say. Alas, the "no known issues in this build" message doesn't say much, since no build of 10.4.2 had any known issues in the release notes.