You may able to join Facebook from your iPhone or iPod Touch, but have you ever try to use FaceBook Chat from your iPhone or iPod Touch smart Phone? If you use facebook address from your safari browser such as using m.facebook.com, We believe that you are unable to make a chat or make IM on FaceBook Chat or FaceBook Messenger.
Don’t worry, you still able to make a chat in FaceBook Messenger through Web Base All in One Messenger. One of example of this All in One that supports facebook chat is meebo.com.
Yes, just use your iPhone or iPod Touch safari browser and pointed your Safari to www.meebo.com and choose facebook chat Messenger Service in there n Enjoy to chat in FaceBook from your iPhone or iPod Touch.