There is a new tool to take .Net developed modules and convert them to the Java bytecode for running inside a J2EE environment.
I suspect that any code developed for this tool would have to be developed specifically for it, so I don’t quite see the benefit to be gained as opposed to just writing it in Java in the first place. I also suspect its only deployable on Windows app servers anyway, but I might be wrong about this.
Whatever the case it certainly adds a new angle to the current influx of J2EE and .Net integration products.
Mainsoft product page