Of course Microsoft is pushing the theory that interop means Works With Microsoft.
From [[Dave Winer]] at [[Userland]]:
The rest of us should just reject that without discussion. I’m perfectly happy to get interop with Everyone But Microsoft. They have an uphill battle to get developers to adopt their tools. Sure some developers will go anywhere Microsoft wants them to go today. More power to them. But for the rest of us, the more Microsoft isolates itself, the more appeal our technologies have to developers who value independence.