In addition to Hervey Wilson, Keith Ballinger and everyone on his the WSE team, who pays attention to Interop at Microsoft?

Jorgen Thelin drives the workshop process which is critical for specification refinement and proving out interoperability with early bits.

Simon Guest helps drive programs to prove out interop with shipping bits.  Matt Powell is adding Simon's blog to the MSDN Web Services blog roll, but he isn't taking my suggestion on blog description... ;)-  So, if you haven't visited his blog yet, here is the description I think he should have:

Simon Guest - I love systems, all systems, short systems, tall systems, efficient and fast systems, but most importantly I love .NET systems and connecting them to legacy systems.