Would be great you could select multiple post types. I'm using a theme that has a couple of additional custom post types related to reviews and videos. It would be great if you could select all three: posts, reviews, and videos. This way any activity will get logged to the calendar. In the future maybe you could color code each type. So looking at the calendar you could see say yellow for posts, green for reviews, blue for videos. Not sure how you'd handle multiple types on the same day but just a thought.