I know that it's open source, and open, interoperable protocols are a good thing.

But. I don't think IMAP is the real competition here. This is, for most people, a solved problem, and a problem that's been solved by exchange and gmail.

So for better or worse, showing you're better than IMAP doesn't cut it. You have to show you're better than exchange.

One of the things I don't understand is why email protocols were allowed to languish for so long, making proprietary groupware suites practically mandatory for getting work done.