If you want an invitation, all you have to do is leave a comment with your contact info (cleverly disguised so as to avoid the spambots) on my original post. I’ll randomly select two winners on Monday.
It looks like Joost is marching on towards a final release soon. Version 0.9.1 came out today. It doesn’t look like a major update from 0.9.0, but at this rate, we can probably expect Joost 1.0 to hit within the next few months. But for now, you still need an invitation to play.