Just recompiled Max.NET with .NET 4.0 and its looking good so far. I'm switching all of my (remaining) projects to VS2010 so next build will be able to load .NET 4.0 assemblies, albeit Autodesk.Max.dll will still be 3.5 so VS2008 users can still use it.
Marsel Khadiyev (Software Developer, EPHERE Inc.)