People interested in Hacker News (and based in Melbourne) may also be interested in some of these upcoming events and meetups...
http://thehive.org.au/
Monthly networking for entrepreneurs, with a guest speaker who talks about their startup. The podcast from the session with Steve Sammartino from Rentoid.com has some interesting anecdotes on how he publicised his startup.
http://siliconbeachaustralia.org/
Fortnightly meetups to discuss tech startup ideas (the Melbourne website is broken, so I am not sure if this is still happening).
http://www.tedxmelbourne.com/ (November 20th)
TEDxMelbourne is an independently organised TED-like event under license from TED.com
http://www.ruxcon.org.au/ (November 20th, and 21st)
Ruxcon is the premier technical security conference in Australia. Like Defcon, but held in Australia.
http://groups.google.com/group/mclbb (first Tuesday of the month. Next one is on November 9th due to the Cup Day public holiday)
Interesting technical talks held at lunchtime in. The next ones are on Hadoop and Python games.
http://upcoming.yahoo.com/event/440359/
Melbourne Association of Software Testers (last Wednesday of the month)
Monthly meetup at Beer DeLuxe to talk about software testing and related topics (and drink beer). Some Agile testing enthusiasts guaranteed to be at each meeting.
http://trampolineday.com/ (next one is expected to be sometime around March 2011)
Trampoline is a self-organising un-conference for those who find the world interesting, have something to offer and share, and have an inquisitive mind.
Hopefully this comment is not too off-topic for Melbourne-based readers. I have already met several of the commenters from this HN story at some of these events. If you have any more, please post them in a reply to this comment.
Earplugs are definitely a simple solution, but have the drawback of not being highly visible to people around you.
When I need to concentrate, I wear my big Sennheiser headphones - often not even plugged into an audio source.
They are very comfortable for long periods, block out most of the noise, and (best of all) they send a clear "do not disturb" message to anyone thinking of interrupting.
Matthew Inman (who co-founded SEOmoz) did a web comic that neatly captures the design process when non-designers insist on micro-managing design decisions.
Happy Newtonmas!