Now that Visual Studio 15.3 has been released (along with a few updates), Microsoft is turning their attention to the newly announced 15.4 version of VS2017. Currently in a preview state, 15.4 focuses on adding support for the forthcoming Windows 10 Fall Creators Update (FCU) which is due to arrive Fall 2017. While 15.4 Preview is available for download by all interested parties, taking advantage of the FCU specific functionality will require becoming a Windows Insider and the download of the corresponding Windows 10 SDK (alternative link).
The current stable release of VS2017-- 15.3.x-- includes support for .NET Core 2 but UWP apps had yet to support .NET Standard 2. That changes in 15.4 which allows the development of UWP apps that target FCU and .NET Standard 2. This support should promote code reuse and make it easier for developers to write libraries that are more easily supported across multiple platforms (Mono, Xamarin, .NET Framework, .NET Core, etc.).
While this is a preview release, it should still be noted that there is a serious Known Issue with this build-- the XAML Designer is disabled for UWP applications that set a minimum target of FCU. This means that non-XAML UWP apps can target .NET Standard 2.0 as previously described, but UWP apps with XAML will have to wait a bit longer for full support.
Developers writing applications with Windows 10 users in mind should benefit from the addition of a new template, Windows Application Packaging Project, which provides the ability to take an existing Windows project and package it into an appx container for submission to the Windows Store or other distribution methods. The application being packaged does not need to be a UWP app. This template does require the target platform to run Windows 10, but developers now have an easier to way to distribute their apps without resorting to a traditional Win32-style installer.
Non-Windows 10 Specific Additions
The Xamarin Tools for Visual Studio have been improved to include support for the Xamarin Live Player which makes it much easier to rapidly prototype apps with VS2017 and a mobile device. When installed on an Apple or Android device, the player will read a QR code off of the screen of the workstation running VS2017, providing a fast way to test code under development on an actual mobile device without first deploying it to an app store.
The formerly standalone "Control Click Go To Definition" Power Tool is now a part of VS2017 proper. As of this release C#, VB, and Python are supported. To use this feature, hold down the CTRL key while hovering over a line of code in the IDE and you will be able to easily navigate to its definition.
As is the case with preview releases, this is not licensed for a "go-live" situation and should not be used in production environments. Installing VS2017 Preview can be installed side-by-side with a production copy of VS2017 but risk still remains and probably should not be done in mission-critical environments. Full release notes for this preview are available and should be consulted if you are unsure as to whether or not to install it on your local machine.