I just discovered this while using Google's new voice search in Chrome. After asking "when is Father's Day?", I was given the screen above. Under the card is the option to add a reminder to Google Now. Once you click that, a message pops up stating that you will be reminded one week prior to the searched date. This seems to be the case for any "when is..." query in Chrome. Anyone know any other tricks involving reminders?
Edit: Looks like Lifehacker beat me to it.