@Vangelis: It looks like CNet's Download web site, annoying as it is, does host a mirror of the most recent version of PlaySound (1.6.7) before development ended. You can download the application from their site at
http://download.cnet.com/Play-Sound/300 ... 25096.html for now.
@Jay: Thanks for the suggestion. Yea, I'm sure I could modify the plugin to use the "afplay" built-in command-line utility instead of using the appscript Python libraries to send AppleScript commands to Play Sound. It's been a while since I looked at the Announcer plugin code (2013 in fact), but I'm pretty sure I considered using "afplay" and decided against it because it was easier to launch Play Sound, sending it a file path and telling it to run in the background than it was to execute afplay from a Python subprocess and deal with tracking the child afplay process from within the plugin code. I may have to look at using afplay again though.