Unmanaged Side of Longhorn
With Longhorn, Microsoft is pushing us to managed code. I said earlier that I wasn't aware of any new unmanaged API being written.
Ian was able to find some of the new WIN32 unmanaged calls added to Longhorn in prerelease header files. There are some new calls, mostly in COMMCTRL, which handles common controls, and some in the KERNEL, but very few. These look like APIs that must have been added shortly after Windows XP before the real designs for Longhorn ever took shape.
There are no new GDI calls, underscoring the fact that GDI is becoming obsolete, and being replaced with DirectX.
Much of the old unmanaged world is being rewritten. The explorer is rewritten and all managed. The new command line shell is managed, MSH, but with a whole new syntax. The old shells (CMD and COMMAND) will likely remain unmanaged.