I think most entrepreneurship events will consist of majority HN users so maybe they are already meeting each other at some many other events that no one has saw a need to create an official HN one (I have not heard of one yet). But I think it's a great idea :) and I would love to attend it! Maybe there should be a HN pre-meeting before each entrepreneurship event since we're all most likely to be there already! Speaking if event, if any of you are interested in meeting me (I'll wear my HN username for easy identification), a fellow HN user, I will be at this entrepreneurship event on Nov 11 :) http://rainmakers3.eventbrite.com/
Not that I know of. I've hosted a few HN meetups, but in a completely informal fashion, by just posting the date/time/location on HN. Last time was a couple of years ago, though, and the community was a lot smaller then so things didn't fall off the New page as quickly.
Meetup is super useful because people can join the group, and then be notified of future events. Which is much easier than getting a thread to survive on the front page for a day.