Native rendering plugin doesn't work on Linux

Hi, I've been trying to port some code to Linux now that Unity 4 supports it. I need to do some high performance rendering, so I'm relying on some callbacks from Unity - namely the ones specified here http://docs.unity3d.com/Documentation/Manual/NativePluginInterface.html. I'm using Ubuntu 12.04 for my tests.

The problem is they are not getting called at all. At first I though the problem was within my code but then I tried the RenderingPluginExample40 that comes with the installation and the result was the same.

I'm getting the feeling plugins aren't fully supported on Linux as the rendering plugin example doesn't even compile as-is and there are no defines for Linux either - the code assumes you're on Mac OSX if you're not on Windows and the OpenGL include is wrong. After I fixed it I compiled the .so with

 g++ -c -fPIC RenderingPlugin.cpp -o RenderingPlugin.a -lGL
 g++ -shared -Wl,-soname,libRenderingPlugin.so -o libRenderingPlugin.so RenderingPlugin.a

I've verified that the shared object loads correctly and the methods in the example C# script that use DllImport are executed - only the rendering callbacks from Unity aren't.

Needless to say, both my code and the example run fine on Windows.

So the question is, are plugins (and callbacks) fully supported for Linux?