The Chandler folks are close, but falling into the same mistake that the mozilla folks made: attempting to build the monolithic app-that-does-everything. A corrolary is one of Zawinski's laws: every app will grow until it can read email.

I'd wish people would stop doing this, and focus on things that are imporant: the interfaces and contracts between useful, not-currently-existing components. Each app should have an http server, and be able to be an http client. Each app should provide and utilize RESTful, HTTP-based interfaces. With platform-specific ways for applications to register with a common server, Chandler would only need to create a platform which existing applications [mail, RSS, IM, &c.] could GET/PUT/POST/DELETE against.