You need to edit the file /User/Library/Preferences/com.apple.Preferences.plist on the device -> whether you use a jailbreak to achieve this or merely some iTunes backup editor is up to you. Add the following boolean key as ‘true': KeyboardEmojiEverywhere Then merely go to the Keyboards section of the Settings app, hit Japanese, and turn on Emoji. Will work for any text field/view in the OS, including on websites, AND including the titles of items on SpringBoard (e.g. if you save a bookmark to the home screen).The easiest way to do with will probably be to run your iPhone as an SFTP server, which is as easy as installing a package or two on your jailbroken phone. After that it's just a matter of editing the config file and emoting to your friends, again and again, via creepy little icons. [Steve Troughton-Smith via MacBlogz, Image from MacRumors]
Emoji: if you've never heard of it, that's because you're probably not living in Japan, 12 years old, and a highly social schoolgirl. An emoticon standard that is widely used in the country, it was included in the iPhone 2.2 firmware on the SoftBank network, but not for anyone else. Apparently fed up with his lack of ability to graphically express his numerous LOLs, a developer has figured out a simple tweak to enable these icons system-wide, no matter which carrier you're with. Naturally, to show anything other than unintelligible strings of Unicode the recipient's phone has to support Emoji emoticons, but apparently all 2.2 iPhones, hacked or not, can display the icons. The patching process, after the jump, isn't terribly complicated.