Some folks may find this useful. I use gcal all of the time and thought this tip was way cool. I know my geek stripes are showing.

Google Help > Calendar Help > Features > SMS

How do I create an event via SMS?

To create an event via SMS, simply send a text message containing your event’s details to the shortcode “GVENT (48368).”

For example, if you send a message with something like “Shopping with Sarah at Monterey Market 5pm Saturday,” Google Calendar can figure out what you mean and pop the new event into your calendar.

Please keep in mind that this feature is only available in the US at this time.