I just saw this on the Ableton Forum:
We just released the latest Live 8 version, Live 8.1.
The main focus of that 8.1 version is the release for the "Max for Live" product. Additionally, Live 8.1 contains a bunch of bugfixes compared to Live 8.0.9. (A corresponding change log will follow soon).
Please ONLY update to Live 8.1 if you own a Live 8 full or suite license, as 8.1 does not yet support Lite and Intro licenses. Live Lite and Live intro support will be included in a later bugfix release.
I also saw the following note on this download page:
Live 8.1 introduces a new file format - documents saved with Live 8.1 or newer will not be able to be opened in older versions of Live.
Electronic Music Artist, Composer, Sound Designer