By the hammer of Thor!
I just looked, and I couldn't find the calendar or the submit page.
Okay, with Google, I was able to find both:
Calendar:
http://www.storynet.org/Events/Calendar/
Submit an Event:
http://www.storynet.org/contact/submit.php
Working backwards, I figured out the path from the front page.
First you have to mouse over "Events" to see a "Calendar" link.
Or you click on Events, and "Calendar of Storytelling Events" is the 4th link down.
I stopped posting events to NSN long ago, because of the "90 days previous" policy. Most of my gigs are scheduled less than 90 days in advance, so I don't bother.
I do use Storyteller.net, also Craigslist, Upcoming.org, MySpace, Tribe.net, and Going.com. They are all self-service and instantaneous.