This was pompted by a couple of recent questions where the answer amounted to "there seems to be no API for that" in both cases.
Retrieving Windows version "1511" was about retrieving the "Version 1511" string prominently displayed in the Help / About boxes of system apps from Notepad to MMC since the November update. The only proposed workaround was to read it off an undocumented registry key.
How to detect whether Windows 10 features are currently enabled in the console was about a console app detecting whether it's running under the "new" console (ForceV2=1) vs. the legacy console. An incomplete and unsatisfactory workaround (that I posted there) was to check whether the console window allows itself to be resized wider.
I would expect that there must be more cases of such new features that the published APIs haven't caught up with, yet. Examples welcome, references and known workarounds even better.