This use case could be seen as the super set of the previous use cases but that would be too simple. Once JuggerNET is part of your toolkit and you have purchased an enterprise-wide deployment license, you have so many fewer constraints when it comes to choosing products that you can start reaping benefits beyond the specific API integration.
You might already have gotten an idea about the benefits of language-neutral development via .NET, but now Java can be an almost seamless part of it.
What if you could largely ignore the language boundaries between Java and .NET and extend your .NET applications to incorporate Java?
So your enterprise bus is written in Java and you have many .NET applications. Not a problem.
Why not use your standard JMS provider for connecting your .NET client application to a server?
The other group wrote a portable validation library in Java. Couldn't we use that in our .NET app?
Being able to leverage free Java products in your .NET applications can allow you to reduce the number of third-party products you rely on. That can translate into tremendous cost savings over time that go far beyond the mere tool benefit!
And allow us a final quick pitch for Codemesh's JunC++ion product: how about adding C++ to the mix?