Changing T9 language while writing messages

Hello, since it happens to me to send SMS messages in my language (italian) but also in english. I would like to know if there is a way to change the T9 dictionary corrections while in the messages application.
I saw once an iPhone 2G doing it: on the bottom left side of the keyboard, there was a "globe" touch button that allowed to switch between local language and english.
I do not see this touch button in my new iPhone 3GS...
Thanks!