My wife is an Italian Professor. She entered in USA on July 2006 with a J2 VISA. She left USA on October 2006.

On July 2008 she entered USA with a J2 VISA. She changed her VISA in J1 on January 2008. She started to work in a USA University on January 2008.

I ask:

She is eligible for Tax exemption treaty?

Read about the U.S. and Italy tax treaty:
Your U.S. Tax Return: U.S. Tax Treaties for Professors, Teachers and Researchers