For me (on iPhone 5 running iOS 7.1), if the Calendar app is not on the recent apps list and its state isn't saved then launching it shows the last view I used (let's say Monthly with a list of events at the bottom) and has today as the selected day. However, if the Calendar app is on the recent apps list and its state is saved then going to it brings it up with whatever the last day I was looking at as the one being selected.