There's not so many people there yet though

oooh send me an invite!

I don't have any

But I can add you by email. AFAIK that means that you will get an invite when it becomes available

I think so far only Google employees have invites to send

my office mate is an intern in nyc right now so I got it from him

I think they are open for invites now. Send you email in a private message, and I will invite you

I have also an account and I am not that impressed. I mean, Google Wave was also a "great" product, but not really what people wanted

and I think Google+ is very similar

I don't understand how they can have a social network where they do not allow everyone to sign up..

Per They probably will very soon

Per - didn't you see The Social Network - it has to be "exclusive".