I run Hackers and Founders, Silicon Valley and SF. http://hackersandfounders.com. We've been going for around 2 years and have around 900 members. About half come from HN, the other half through word of mouth, or Meetup.com. I don't make any money off this, I just enjoy having a beer, and geeking out with startup geeks every 2 weeks.
I also try to contact other people that post meetup listings on HN, and try and help them get off the ground if I can. I've been in contact with meetups in NY, Chicago, Indianapolis, Tel Aviv, and Wellington, NZ.
The churn on the front page is so great that unless you're in a major metropolitan area, you're not going to get enough upvotes to have a meetup posted. So, it would be helpful to those in non metropolitan areas to have a venue to post their events in a place where it wouldn't fall off the front page in 8 hours at best.
Honestly, just a simple "events" tag at the top of HN would be great, and allow people a self-referencing post Ala "Ask HN:..." I think there's a big demand from HN readers for something like this.
For instance, we just hosted a meetup for 6 guys coming in to SV from the UK for a week to check the area out. The only reason that they knew about Hackers and Founders was because our first event 2 years ago was a meetup before startup school, and the organizer of the group came to the meetup before startup school. The guys that came in were really cool, and I picked up a lot of great ideas for my startup from them.
I try not to announce hackers and founders meetups here anymore much, because I really don't want to pollute the front page with event listings. We have events every 2-3 weeks, and I think it would be a pain in the ass for HN readers to read event announcements from us every 2-3 weeks.
I'm pretty sure that Brennan that runs the Indianapolis meetup and Dave that runs the NY meetup don't post here that often either. Brennan uses Meetup.com and Dave uses a twitter feed + Anyvite. The Chicago meetup uses a Google group.