ASP.NET Core Community!
First of all, you can find all the code and the announcements on Github.
Official ASP.NET Core organization can be found here – http://github.com/aspnet/
Announcements are posted here: https://github.com/aspnet/Announcements
Announcements for .NET Core follow the same pattern: https://github.com/dotnet/Announcements
Entity Framework core code can be found here: https://github.com/aspnet/EntityFramework
You should definitely follow the official .NET Blog – https://blogs.msdn.microsoft.com/dotnet/
YouTube Community Standup
Every week guys from Microsoft do open community standup about current status of ASP.NET Core, progress, plans etc.
Definitely worth to watch if you wanna find out more about ASP.NET Core – http://live.asp.net/
You can find tons of cool stuff related to .NET Core and .NET on Channel9:
You should also join over 5000 other developers on Slack:
Even Damian Edwards (ASP.NET Core PM of PMs??) and David Fowler (ASP.NET Core architect) are there, among other great guys from Microsoft and the community!