I downloaded and installed Grasshopper just to try it out! Installation was very smooth, without any of the difficulties I came upon every time I tried to install a non-Microsoft development tool. Well, ok, us, Microsoft oriented developers, may be a little spoiled! I just clicked on File-New-Project and there it was! VB for J2EE and C# for J2EE Projects! Amazing. My "Hello World" sample project was up and running on Tomcat (included in Grasshopper 50MB installation package) within 5 minutes! Right clicking on solution explorer allows to adding a reference to .NET and Java files! But one of the most astonishing things I have even seen in my humble carrier is this:

Microsoft.VisualBasic.jar !!!

Now I'm convinced!!! Anything is possible!
Unfortunately, since Grasshopper is based on Mono Project, it is available only for .NET Framework 1.1 and Visual Studio 2003. I read somewhere in Grasshopper forum that version for .NET Framework 2.0 is expected by the end of this summer.

About Grasshopper
Grasshopper, the freely available Visual MainWin® for J2EE™, Developer Edition, is a plug-in to the Visual Studio .NET IDE that enables .NET developers to port existing ASP.NET and server applications to J2EE servers. Developers can also use .NET skills to develop, debug, and deploy server and Web applications from within the Visual Studio .NET development environment, and run applications natively on the J2EE platform. Grasshopper is designed for small user group deployments.