OK, here's the real deal.

"iptables -L -t nat" will show the NAT rules that
have been configured.  I.e. what connections are
permitted, and how they are done.

"netstat -M" would show the _active_ connections
that are _currently_ being masquerated/nat'd at
this time.  I.e. what connections are actually
in use _right now_.

"netstat -M" only works from ipchains.  I'm not
sure if it would work if you use iptables and
then loaded the ip_fw_compat module.  Might be
worth a try.

*phew*

Hal