I love Notification Center, but there's one thing that's bugged me about it since its introduction in iOS 5 and that thing is even worse in iOS 6: Notification Center always shows your contacts' birthdays no matter what.
In iOS 5 this wasn't too annoying, because most people probably didn't have a birthday listed for every contact in their address book (just the important ones -- like close friends and family). However, with the introduction of Facebook integration in iOS 6 (if you've enabled it), if a Facebook friend has their birthday listed, it's now in their contact card in iOS 6 Contacts. And if it's in their contact card, it will always show up in your Notification Center.
Now, I'm assuming this is just a bug that Apple has yet to kill (then again, it's been around since iOS 5, so maybe it's a "feature") but Apple needs to kill it quick. Why? Because, like other "features" of Facebook integration in iOS 6, this one too gives you plenty of information you don't need and displays it front and center in your Notification Center.
Take for example the screenshot above. On that day, Notification Center showed me that three of my contacts had birthdays. Because a birthday is an all-day event, they are shown before other timed events in my Calendar. This is just more clutter that pushes relevant information (like meetings) off screen.
Now keep in mind that I'm the kind of guy who only connects with people on Facebook who I know in real life. I've got fewer than 200 Facebook friends. That's still 200 extra all-day events that are going to show up in Notification Center that I don't want to see. Given that many people (especially younger users) have 500 to 1,000 Facebook friends, they could potentially be seeing two to three birthdays every day -- again, this would obscure more relevant information.
To be clear, this isn't just a Facebook birthdays problem. Notification Center had this problem before Facebook integration. The Facebook integration just makes it that much worse. But simply disabling Facebook integration will not stop all birthdays from showing up in Notification Center.
As noted by one of our commenters, you can hide birthday calendars from the Calendars app in iOS by selecting the "Calendars" button and then deselecting the Facebook birthday calendar and the "Other" birthday calendar, but this doesn't actually stop those birthdays from showing up in Notification Center (though it should). That's why I'm assuming this is still a bug that needs to be squashed. But let's squash it already. It's been a year.