To be like RSS, it would have to be some open tech that is free to be used by anyone without royalty, with no individual, corporation or standards body that can make your development work obsolete. To me, as a developer, that's what open means.

If Apple can deprecate and then remove an API, or not approve an app because it doesn't conform to a rule that didn't even exist when I wrote it -- that's very far from the ideal.

Lots of APIs these days are like that. And since they have corporate sponsors, they're the ones they talk about at tech conferences. Because they can pay for sponsorships. That's how the conference promoters get paid.

I have a reason for asking this question -- I'm wondering if there's enough open technology out there that's not corporate-owned that we could have an interesting meetup among interested parties and get some good cross-pollinating done.

I think this is the core of what Stallman's free software idea is about. I really don't care that much about software, though I respect that he does. What matters to me is that I can ship something and have it keep working indefinitely, without worrying about someone outlawing my work. That kind of power always gets abused (I wonder why anyone would think it wouldn't).