Unity 3.0.0f1 dll build error

I'm trying to build my project for the web with Unity 3.0.0f1. To communicate with a flash player I'm using a .NET dll Jayrock.Json.dll

When building this in Unity 2.6 it works fine but in 3.0.0f1 I get a error message:
ArgumentException: The Assembly System.Web is referenced by Jayrock.Json. But the dll is not allowed to be included or could not be found.
UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache) (at E:/BuildAgent/work/68355d6e5d19d587/Editor/Mono/AssemblyHelper.cs:52)
UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache) (at E:/BuildAgent/work/68355d6e5d19d587/Editor/Mono/AssemblyHelper.cs:55)
UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch) (at E:/BuildAgent/work/68355d6e5d19d587/Editor/Mono/AssemblyHelper.cs:86)
UnityEditor.HostView:OnGUI()

I know Unity 3 is not officially supported yet but does anyone know what's going wrong? Or is this a bug in de new Unity RC?

 

They changed the web security structure for U3, so looking at that error suggests that the DLL is not allowed to be used for U3 in a web player environment. This is a core change between U2 and U3 so I doubt this is a bug but is a feature.

 

So what yours saying is that Unity 3 doesn't support JSON anymore?