iOS' notification system it set up so when you miss notifications, they'll stack up on the Lock screen and in Notification Center until you have a moment to look back at all of them.
The notifications are separated with padding and are plain Jane, but for those that want to switch things up a bit and make notifications look a bit more modern or appealing, a new jailbreak tweak called RedesignedNotifications will let you personalize the look of your Lock screen and Notification Center notifications to your own personal preference.