Its kind of like the first 6 months you are taking care of a baby, they really don't do much but need to be attended to constantly, and usually you can take solace in the sheer love of what you are making, but sometimes at 4 am when the little thing is crying and all you want to do is get some sleep and then you have to get up and go into work the next day anyway, having someone to share the experience with is great.
I like the idea of meetups, but I'm in the Hartford area, not sure there are a ton of startups around. What would be kind of cool though would be some kind of "Who's working on their startup now" list, maybe even here on YC's site, where people could sign-in when you start working and we could have some kind of quiet community, even if its just the ethereal prescence of our names.