RAD Studio XE8 (Original Release and Subscription Update 1 versions) runs on the latest Windows 10 Insider Preview Build 10158. The Update/Install, on my MacBook Pro running Parallels for the Mac Desktop, took a while, at least 15 minutes time (but I did not run a clock as I was working on other computers at the same time). There were several reboots in the process. So, you’ll want to “Sit back and relax” according to the Microsoft Upgrading Windows screen.
I tested the already installed RAD Studio XE8, the IDE launches without a problem. I built "One Button" apps for VCL and FMX, ran without a problem. I tried a few sample of the sample apps and used the Windows 10 style – all good too. InterBase XE7 64-bit developer server– runs as a service with no issues.
I used GetIt (Tools | GetIt) to download the Delphi Windows RT library. Grabbed Marco’s sample app from his dropbox link. Build the sample – Notification works. Note: Microsoft has renamed the "Notification Center" as the “Action Center” even though when you hover over the toolbar icon – it still reports “New Notifications Available”. Read Marco’s blog post at http://community.embarcadero.com/index.php/blogs/entry/windows-10-notifications-from-a-vcl-app-with-the-winrt-api for additonal information and the link to the sample app (https://dl.dropboxusercontent.com/u/133855/WinRTCheck.zip).
A final note - in Windows 10 build 10158, Microsoft Edge now has a graphically stylized lower case “e” for its icon on the toolbar