The Gelfand Correspondence Program in Mathematics is now back in operation as E-GCPM (Extended Gelfand Correspondence Program in Mathematics.) You can see a description of E-GCPM and how to enroll at http://www.EGCPM.com.
The books prepared for the program remain available. These books are described at http://gcpm.rutgers.edu/books.html.
You may see a description of the program as it existed from 1990 until its suspension at http://gcpm.rutgers.edu/former_description.html.
If you have questions, please contact Tatiana Gelfand by e-mail. Her address is info-EGCPM at dimacs.rutgers.edu.