The MSBuild Conference always gets me motivated to dig deeper into the underlying platform. Here any my links and notes to get started:

Chat
https://gitter.im/dotnet/csharplang

MsBuild C# 9 - "C# Today & Tomorrow"
https://mybuild.microsoft.com/sessions/cea64369-aed9-4497-83f1-d3cf1360a57d?source=sessions

Status:
https://github.com/dotnet/roslyn/blob/master/docs/Language%20Feature%20Status.md

Issue included in c# 9
https://github.com/dotnet/csharplang/issues?q=is%3Aopen+is%3Aissue+label%3A%22Proposal+champion%22+milestone%3A%229.0+candidate%22

Compiler
https://github.com/dotnet/roslyn

Runtime
https://github.com/dotnet/runtime

Play with the features
https://sharplab.io/#v2:EYLgtghgzgLgpgJwD4AEBMBGAsAKFygZgAJ0iAxAewqIG9ciGTjKKAKFDABiIDcIAbAK5wAlLSIBfXFLw5CJNEQDCteo3koALEQCyrMXRyNj5KkQBmRALxEAdnADurAEQAJOP34UAhM5EBuNQYZCSA==

Visual Studio Blog
https://devblogs.microsoft.com/visualstudio/

Blog talking about latest bits
https://wakeupandcode.com/net-5-0-vs2019-preview-and-c-9-0-for-asp-net-core-developers/