Código:
$ git clone git@heroku.com:quiet-spring-xxxx.git
Cloning into 'quiet-spring-XXXX'...
Warning: Permanently added the RSA host key for IP address 'XXX.XXX.XXX.XXX' to the
list of known hosts.
Permission denied (publickey).
fatal: The remote end hung up unexpectedly
El entorno de trabajo es Windows XP SP3 con el software de heroku (mingw32)
Alguna idea

Saludos