Unless you are or know a developer, you'll have to wait until sometime in September for the official iOS 8 to hit your iPad or iPhone. However, that doesn't mean you can't get some of iOS 8's new features on your iOS 7 device right now. For example, the new Notification Center, which I'll show you how to install below.
For this to work, you'll need to follow our guide on jailbreaking iOS 7.1, 7.1.1, or 7.1.2 on your iPad, iPhone, or iPod Touch. It's as simple as connecting your phone to a computer and clicking a single button. Seriously, it takes less than two minutes if you've got fast internet.
Once you're jailbroken, open Cydia (the official app store for jailbroken devices) and Search for Notific8. Once you find it, tap on Notific8, then Install and Confirm.
The download will start and the app will run. After which, select Restart Springboard for the effects to take place.
When your device boots back up, you will now have the iOS 8 Notification Center.
So what's different? For starters, the All and Missed tabs are now combined into a single tab called Notifications.
Additionally, the gaussian blur is more transparent, widget and notification titles now have a background bar (a bit glitchy), and a new edit button exists at the bottom, which grants you quick access to your Notification Center settings (in iOS 8, it allows you to manage widgets).
To remove Notific8 and revert back to your old Notification Center, go back to Cydia, tap on Installed, select Notific8, and tap Modify -> Confirm -> Remove.
Then simply Restart Springboard so it's completely removed.