Microsoft announced  Wednesday it is extending its "identity federation" services to its college and university clients who use Live@edu, the company’s integrated e-mail, calendar, instant messaging, and online file storage suite. An “identity federation”  is a group of institutions that allows students, researchers, and employees who need to access password-protected Web sites at multiple institutions to use a single log-in identification and password. With thousands of institutions worldwide already using Live@edu, the federation is already built, said Cameron Evans, Microsoft’s chief technology officer, in an interview yesterday. Evans compared the service to the driver’s license system, where a person who acquired a driver’s license in Maryland can use it to drive or verify I.D. in each of the other 49 states, rather than having to acquire and carry around 50 different licenses. Identity federations are currently a hot topic in campus IT; Educause last year recognized several companies that had applied the concept to higher education with its Catalyst Award .