call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'gcal_test' was given in /var/www/includes/menu.inc on line 348.

This is because you left in a menu item for gcal_test on line 74 of gcal.module but you commented out the function gcal_test directly below it.

I suggest either uncomment the gcal_test function or comment out the associated menu item until you have gcal_test doing what you want it to do. Currently, once uncommented, it returns an e-mail address [randomcharacters]@group.calendar.google.com