I am using proxytunnel with CYGWIN at both ends and OpenSSH 4.3
It works like a charm, it is true, although I got a message error in line 2 of ~/.ssh/config
so I change it for:

Protocol 2
ServerAliveInterval 60

and that works for me.
It might help other people.

Marco

Yeah... this option has been renamed/replaced some time ago... The documentation hasn't been updated yet. I'll look into that sometime soon ;)