It is true that the .NET platform is doing away with DLLs and actually, it's doing away with tradition ActiveX also. It will be based on objects called Assemblies.
If you have an actual ActiveX component, you can call this from both LabVIEW 6.1 and VB6. However, if the object that you have built was built in the .NET environment, then it is an Assembly object. And, since this technology was released after both VB6 and LabVIEW 6.1, neither platforms support .NET controls yet. VB6 will most likely never support Assemblies, although I assume LabVIEW will as future versions are released.
J.R. Allen