"An extremely convincing phishing attack is using a cross-site scripting vulnerability on an Italian Bank's own website to attempt to steal customers' bank account details. Fraudsters are currently sending phishing mails which use a specially-crafted URL to inject a modified login form onto the bank's login page.
The vulnerable page is served over SSL with a bona fide SSL certificate issued to Banca Fideuram S.p.A. in Italy. Nonetheless, the fraudsters have been able to inject an IFRAME onto the login page which loads a modified login form from a web server hosted in Taiwan. "
Good real life example of XSS being used.