So I decided to take Windows 8 for a test drive and installed the Consumer Preview.
I also installed Visual Studio 2012 RC and all my usual dev tools.
Unexpectedly the whole environment is quite stable and all my favourite tools seem to be happy with the new OS.
The only exception is OpenVPN Connect, it installs without problems and even connects to the VPN Server, but routing is not working.
Tried multiple things like running under compatibility mode, setting delays in the configuration file, using the OpenVPN GUI, installing the 64bit beta version. But to no avail.
I then came across this forum thread where someone suggests opening the Network Adapter Applet (Control PanelNetwork and InternetNetwork Connections) before connecting the VPN Client. And guess what…it works.
Some obscure service must start when the applet opens that allows the client to connect. Hopefully this will be fixed before Windows 8 is out, but for now this workaround works great.
As Yaniv Kunda pointed out in the comments the “obscure” service that starts when you run the applet is “Network Connections” service (Netman), so set it to Automatic startup and it should fix the problem.