Good question. There are some plugins for VS that allow production of other code, such as SapphireSteel Software's Amethyst (allowing Flex development with VS) so it's only natural to ask if there was a plugin for a language as popular as Java.
After searching around the web for a bit (damn NerdSniping :P) I found something very interesting: Grasshopper, a MSIL to Java Bytecode crosscompiler that allows running VB and C# 3.0 webapplications on Java Application Servers and also extends VS to work with Java Bytecode (debugging capabilities, IntelliSense for Java classes, etc).
Perhaps someone else has some firsthand experience with this product or could give some more information regarding the actual capabilities of the crosscompiler.