There is another .NET and Java interop(erability) article over at MSDN.
This one talks about Enterprise Interoperability: .NET and J2EE.
I believe Interoperability is the "buzzword of 2004" (as Web Services was for 2003), so here is the article's definition:
"Interoper
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ability: The capability to communicate, execute programs, or transfer data among various functional units in a manner that requires the user to have little or no knowledge of the unique characteristics of those units."?ISO/IEC 2382 Information Technology Vocabulary
I think the quote "Interoperability is Inevitable" is highly applicable to today's application development landscape.