What's the big deal with IAsyncEnumerable<T> in .NET Core 3.0? 

[HttpGet]
public IAsyncEnumerable<Product> Get()
    => productsRepository.GetAllProducts();

ApiBoilerPlate: A Project Template for Building ASP.NET Core APIs 

Stack Overflow is Porting their Entire Application over to .NET Core 3.0 and Utilizing Azure! 

Here are the lists of new APIs obtained:

• 28 New Namespaces
• 359 New Types
• 359 New Types and their 3.845 Members
• 1.044 New Methods in Types that were already there in .NET Core 2.2
• 166 New Fields (mostly Enumeration Values) in Types that were already there in .NET Core 2.2  

.NET Conf is a FREE, 3 day virtual developer event co-organized by the .NET community and Microsoft. This year .NET Core 3.0 will launch at .NET Conf 2019! Come celebrate and learn about the new release. You won't want to miss this one. 

dotNET - YouTube

Blazor WebAssembly is still in preview and is not part of the .NET Core 3.0 release. 

We’re excited to announce the release of .NET Core 3.0. It includes many improvements, including adding Windows Forms and WPF, adding new JSON APIs, support for ARM64 and improving performance across the board. C# 8 is also part of this release, which includes nullable, async streams, and more patterns. F# 4.7 is included, and focused on relaxing syntax and targeting .NET Standard 2.0. You can start updating existing projects to target .NET Core 3.0 today. The release is compatible with previous versions, making updating easy.