really,
That is only half the job what about outgoing.
Your right, from the Little Snitch site:
Little Snitch handles only outgoing network connections on all network interfaces (Airport, ppp, network cards, ...)
Little Snitch intercepts and delays an application network access until you decide to allow or deny the request or handles the request based on an already defined rule.
Incoming connections can be blocked with the Mac OS X built in firewall.
Sounds like the new firewall will let you pick which apps can receive traffic, but will not stop them from sending traffic out, bummer.