not really...
"0.0.0.0:ssh" from the netstat output indicates that it's listening on all interfaces, and the N900 doesn't have a firewall or similar.

and i don't think it's actually the ssh daemon. a timeout usually is due to a networking problem.
but you say VNC works, so the network should be ok...

you can verify that by enabling logging for the ssh daemon, i've described how to do that here. if you don't see any events there while connecting, you have a problem elsewhere.

btw, connecting to the N900 when it's on gprs is a whole different story, because you don't get a public IP for direct access.