From today’s update change log:
Keep your timeline fresh by updating your cover photo on the go.
-Take a new cover photo or choose one from camera roll (iPhone only)
-Fewer taps to start a group message
-Easier to name and find group conversations
So right now you can quickly change your profile cover photo by taking a picture or browsing a picture from your iPhone camera roll.
For those who want to take advantage of the improvements, you can find the update in, or download the Facebook app from, the App Store for free. It’s universal, so it will work with your iPhone, iPad or iPod touch.