>I've read articles that discuss how in large shops where they can afford to have .Net and Java developers on staff, creating the GUI in .Net and the backend using Java/Struts (A Java framework), is getting the best of both worlds.

If you are early in the process cycle it would seem that this sort of mixing of platforms should be avoided if possible. Often it isn't possible, but it shouldn't be an option based on programmer preferences IMHO.

While Interop is getting easier, most of that interop relates only to Web Service interfaces, not standard high performance RPC style interfaces. Using a single platform, whether it's Java or .NET often offers a much simpler development path and more options on how to get the best performance vs. ease of use. Integration always looks good on paper until you have to sit down and implement it <g>...