Just got back from Melbourne, (Toronto, ON), loved it and will return, and I just kept thinking 'If there was a start-up culture in Melbourne, I'd move there in 2 seconds!' - and now there are 6 responding to the thread, :)
Melbourne / Geelong here too! I was impressed when I put the SB blog post above together too. There is a nice range of events happening, and a good amount of code happening too :)
Whilst it's not huge, it's certainly growing. Silicon Beach is a community pushing technology innovation in Melbourne (and the rest of Australia). You can read a little more about it here: http://melbourne.siliconbeachaustralia.org/about-2/ and here: http://www.rosshill.com.au/article/silicon-beach-melbourne/