T9 multitap on the iPhone? Yes! an iKeyEx keyboard available via Cydia, does the trick. After installing all you need to do is hit the Globe on your iPhone / iPod Touch keyboard and Multitap would be one of the available alternatives.
The multi tap keyboard is suitable for Nokia users shifting to the iPhone. This is certainly something we hope Apple puts officially into the iPhone to increase its compatibility and reach. After all not everyone buys that iPhone for the QWERTY, some jut want a cool phone that they can use
Make sure you have activated Multi Tap keyboard in Settings>General>Keyboards>International.
Tested in email, sms, safari. Portrait and Landscape mode. Works!!
UPDATE: Well this isn’t T9 technically. Its simple SMS typing. A dictionary integration would make it T9. But I many would still like it over the iPhone QWERTY.
Via SOS iPhone Source on Cydia