The build at Macworld was unstable, as noted by one of the developers when I asked if I could take it for a test drive. She noted that, basically, the only thing new in between the current version of Messenger and this build was the A/V chat. Also, you may ask how I know the version number. Upon being granted permission to “look around,” I immediately clicked “About Messenger for Mac” to take a screen pic. The developer closed the window and prevented me from taking a picture. She snapped at me that she did not want the version number in the public in the event that the number changed; she cited a previous story as a testament. Despite this, I was able to look at the window long enough to see the version number was 8.0.0 and a build number that I did not have time to memorize. I share this fact just to keep an open flow of information.
The developer told me that there is talk of a beta but no indication of when it would begin. She noted that the new version should be released within the year.