Putty v0.61 (and SecureCRT) added support for authenticating to a remote host via Kerberos:
http://tig.csail.mit.edu/wiki/TIG/InstallingKerberosForWindows#Using_Kerberos_with_SSH
This is a very useful feature in domain environments as it allows for effectively ‘passwordless’ logins if you have a valid kerberos ticket.
I would be very interested in having this feature available in SmarTTY.