List of changes (8.0.1492)
- Fixed compatibility problems with Windows 8.1 Preview.
It’s too early to claim. A Russian user tried this version and it brought down his operating system: http://forum.avast.com/index.php?topic=128222.msg958430#msg958430
Well George, without an official statement, we can only guess… 
I don’t think, in all the years I’ve been on the forum, I’ve ever seen a “beta” initiated this way.
Public download link and no mention on this forum!! ???
forum did not notify the new beta avast
Yup I can confirm that the latest avast beta dont compatible at all. It manage to install and run on Windows 8.1 Preview but open shutdown after restart you will see big problem. Error will appearing without stoping and after the shutdown, Windows 8.1 will not be able to boot up pass the login and password.
For MAC user beware that Windows 8.1 also will effect your mac and cause you to remove Windows Partitions.
I installed this beta version in Brazilian Portuguese Windows 8.1, and a Issue has been found:
→ After initialization of the Avast resident modules, when the user tries to open a program or system functionality that requires Permission Elevation (UAC - User Access Control), the Windows CONSENT.EXE crashes with Address Violation, and Error Report opens. If you disable the Resident modules, the windows operates normally. Once happened an event that froze my system, and I couldn’t even open task manager, needing to reboot system manually.