Yes it is true and it is very cool! Mainsoft has a product called Visual MainWin for both J2EE and Unix and Linux platforms. You can have your ASP.NET applications (using ADO.NET) deployed on a single J2EE platform. Please note, this is not really “calling” any web services that are running on Java.
How does it work? Well for one you can check out this flash movie (and it surely is amazing!). But basically they wrote an IL compiler that takes the IL generated by .NET app (i.e. ASP.NET in this case) and converts it to Java bytecode which then is run “natively” on a J2EE platform.
When you install their product, they add some extensions to VS.NET that allows you to write your ASP.NET application with VS.NET including using all the features you are used to (such as the debugger). You can also jump to the debugger from the java code/component. In the demo they have on the site, the middle-tier of a typical 3-tier web app is hosted in EJB’s and the presentation tier is ASP.NET which is then run on J2EE. The middle-tier is component (jar file) is referenced in the asp.net solution. The deployed application is a war file on the J2EE application tier.
IHMO, this has a lot of value in an Enterprise environment, and should help avoid the whole “religious” debate that some companies get hung over. Has anyone has had a chance to play with this? If so, what have your experiences been? What do you think about this, I would love to hear your thoughts.