Ah, this is good news. I've been waiting for Linux support for this. Microsoft seems to be really, truly (slowly) adopting some Linux support. I see it says that only Ubuntu 18.04 LTS is supported. No other distribution. But that's easy enough to install.
If Microsoft really wants its products to be accepted by many developers and been used in projects, Microsoft has to provide fully open source development tools for Linux or at least free tools, otherwise, many Linux developers will not switch to Visual Studio and Windows.
It seems that Azure Sphere 19.11 is now available in beta.
The main changes seem to be on the development side - support for Linux and Visual Studio for those who have been holding out for this. I didn't see any major announcement for anything on the device itself. It seems like a pain to deploy the beta OS to the device anyway.