A lot of the proposed solutions forget that this is a UX issue that can be addressed with the addition of more contextual information. I'm going to start with

A lot of the proposed solutions forget that this is a UX issue that can be addressed with the addition of more contextual information. I'm going to start with an assumption that for the most part Google knows where you are and where you'll be. (Assume it has access to your email / flights / other appointments etc.) An appointment also has access to who is important to the entry. I'm currently on PDT, will be traveling to CDT and have a phone appointment with someone in MDT later this week. A good user interface for this would show all three times so that I can intelligently talk about the appointment either in an email or on the phone. This is what I mean by 'added context'. UTC is fine for storage, but the who and where is generally interesting (even if you're looking back on things later). This problem seems like it has a simplification to a common fallacy that a single representation of any fact is the only way to display information. I'm not sure it would be significantly too much effort to make a 'super intelligence' understand that.