There are great standards on how to represent an event, specifying what, when, where, who, and even why. In particular, iCalendar (distinct from Apple's iCal software).
I think it's a failure of e-mail software to not have a formatting option to Insert Event (UPDATE 2: apparently, GMail now has this in their new compose window with the text "coming soon" next to it(!)), like you add an attachment, or bold a font. It can sometimes be frustrating to parse someone's verbosity to extract the essential information, and then to manually re-type or copy-paste it into your preferred calendaring application.
Google has tried to simplify this a bit by scanning e-mail text and, if they think they can accurate identify an event, provide you with a "Create event" link that automatically parses it. But usually it doesn't; e-mails are too difficult for computers to parse presently.
It's a bit frustrating that Facebook has a rich events system
My interest is to help minimise my chances of missing events that would otherwise be important to me. I make enough errors transcribing times or dates as is, and more structured information would make others' e-mails less frustrating.
Perhaps popularising iCalendar could become my mission?