Looks like iOS 5 is hiding a bunch of features Apple does not want anyone to get access to, at least for now. First was the hidden Panorama feature in Camera.app and now an iOS developer Sonny Dickson has pointed out another hidden feature of iOS 5. This new feature suggests different words in a bar located at the top of iOS keyboard. This feature works just like the autocorrect feature found on Android devices. You can perform these steps and enable iOS 5′s secret suggestion bar even if your device is not jailbroken.
1. Download iBackupBot
2. Backup your iPhone/iPod in iTunes
3. Open iBackupBot and find the backup, then load it.
4. Find Library/Preferences/com.apple.keyboard.plist and open the file. (if your software isn’t registered you’ll have to press cancel and then it will open)
5. Add in the following code: <key>KeyboardAutocorrectionLists</key><string>YES</string>
6. Save your modifications, and then restore from backup from within iBackupbot.
You can also enable the Panorama mode of iOS 5, details here