A private self-hosted version of this wouldn't be that bad. Imagine that you write the same proxy, and it injects data grabbed from the various API's its hooked up to.

This. The tech described is pretty neat... Give you my email creds? Hell no. But _I_ could do all that myself. I think that would be one way that linkedin could save this - release an easy to set up open source version, say one click to a heroku instance or something. Then one could add all sorts of smart stuff into their own emails.

Agreed. Imagine if you could have other providers snap into this? It's a shame that they're hacking their way around Apple's walled garden, but a self hosted proxy server is a nifty way to add functionality to email.