Invitation-only events are not only for people with "property". They also allow those with "energy" to keep an event from being diluted by those without it. Why shouldn't a group of hackers be able to get together with people they choose? Wouldn't the YC weekly dinners fit this category?
I'm obviously a fan of HN and by proxy, YC... but to be a devil's advocate...
The people at the HN weekly meeting didn't choose to get together with each other, the rich guys who gave them money chose them and told them to be there.
In contrast, superhappydevhouse is open to anyone who shows up.
As one of the organizers for superhappydevhouse, one of my main goals is to keep it from ever becoming an invitation only event. I share a lot of sentiment that Fred Wilson expressed in his blog post.
As superhappydevhouse has grown in popularity and size, this has made finding venues more difficult, we've been extremely fortunate and have had many generous people open their homes and businesses to us.
The "dilution" issue that mellis mentions above has also been a concern, fortunately this hasn't been a difficult issue to address. All that we've needed to do so far is to explicitly state what sort of event we are holding ("A party for hackers and thinkers") as well as discouraging corporate self-promotion and recruiting.
