Re: Kerr Black Hole!
There are plenty of interface definition languages/systems out there today, and they're all pretty much shit.
I'm guessing (no, of course I haven't checked out the code to see for myself) this basically automates the whole thing by storing interfaces and call information in a side channel of data in whatever library/executable you're producing, and uses that data to transform calls from other languages at runtime (or maybe even at compile time if you have that option) so that they just work.
Which sounds pretty cool if you ask me.
And would be a hell of a lot better than either implementing a C-based public API if you're a library writer, or dictating the language users of your code must use, or dicking around with your least hated IDL/RPC/RollingYourOwnShit to get processes talking to each other.
Presumably the big pay off here would be having OS APIs (or any library really) immediately available in any language that the system supports without all the tedious fucking around implementing support. You'll basically end up with language choice being pretty much irrelevant when it comes to writing and releasing code.