I am quoted in this great cover story by Michael Sampson regarding the state of Calendaring options today.
Since the widespread adoption in the 1990s of the various Internet standards for email, we have been able to quickly, cheaply and easily send messages to anyone. We can choose whatever email client we want to use, with little or no reference to the email clients that others select. Plus we can change between email clients at the drop of a hat. Unfortunately that is not the case with calendars, but the situation is changing. The lack of interoperability has been a problem for many years, and in our hyper-connected world it has become a critical problem.