The latest build is available to Insiders who subscribe to the Fast ring. These builds are less polished than the ones that appear in the Slow ring, and "may contain bugs that might be painful for some." So, keep that in mind before hopping into the Fast ring (it's not possible to switch rings without doing a clean install).
"In the latest Insider Preview builds, in addition to registered desktop apps, when you opt into this setting, the majority of open UWP apps are now also automatically restarted as well! To reduce sign-in time, UWP apps are restarted minimized, in a suspended state, giving Windows and other apps more resources to get started," Microsoft explains.
You can try this out by going to Settings > Accounts > Sign-in options and turning on Automatically save my restartable apps when I sign out and restart them when I sign in, which you will find under Restart apps. Then start one or more UWP apps (like Feedback Hub), sign out, and sign back in to Windows.
- Improved the performance for directory listings in \wsl$
- [WSL2] Injected additional boot entropy [Github Issue 4461]
- [WSL2] Fixed Windows interop when using su / sudo commands [Github issue 4465]
In addition, Microsoft is adding the ability to reset your PC from the cloud, and of course the latest preview build includes the usual round of general changes, improvements, and fixes. There are still a handful of known issues Microsoft is working to fix, though it has plenty of time—the 20H1 update will not be pushed out to the public until sometime in the first half of next year.