Email is centralized yes but its also somewhat open. You can send an email to any provider and receive from any provider. You cannot send a message from say facebook to twitter and get a response back.
How about an open nonstandard? To me, there seems to be a lot of open-source innovation these days. To take one example out of dozens, where's the proprietary site that has a more useful proprietary programming language than Python or Perl? I agree with what I imagine your point to be: that standardizing Python up front would have made it very slow to innovate. But being decentralized hasn't made it innovate more slowly.
The issue with email is that innovations have to be adopted independently everywhere for them to be widely useful. But that doesn't have to be the case. You can structure a decentralized system so that any user of the system can deploy innovations on it, that the other users can immediately benefit from, without requiring them to be standardized.
Wave's stuff isn't part of the standard right? So if I were using some other mail service/client I could only use the intersection of both services. Please correct me if I am wrong, I haven't had much exposure to wave (except a brief stint in the private beta where I realized nobody is using it, and therefore it was useless).
