How to customize the header of an iPhone?

Well it sounds a bit weird but I've seen numerous iPhones in which the upperleft corner of the notifications bar has emoji's or the owners names. Its that possible? If so how? Is it a jailbreak feature? Just in case you don't know what i mean i'm talking about the part of the phone (or ipod) where it has the phone carriers name and the bars or where the Wi-Fi signal is.

Yes it's a jailbreak feature:
Don't follow ANY links that people post here that arn't leading to official iPhone dev team websites. Trust me I keep a close eye on all this sort of news and there are only a few sites that are official. All the others will lead to viruses and malicious software downloads.

The best thing you can do is 'like' the following page on Facebook:
Www.Facebook.com/jailbreak101

These guys always post the correct download links to follow on the day of a new jailbreak release and it ends up as part of your news feed so you're never out the loop.their 'notes' section is very resourceful as well, showing you how to get the best out of your Device once it's Jailbroken.

Jailbreak it using evasion and customize it using Cydia