Matt just let everyone know that WordPress.com is now open for public signups. So no invitation is needed to get an account over there. It’s about the time, I guess. WordPress is a great software, so the unnecessary obstacles must be removed. BTW, why are you still reading this post? Just go and get your own WP blog right now. 
So, it is the same like the one that promoted (kinda) by Flock?
I think so. Only now you don’t have to download and use Flock to get the account. It is much easier and pretty straightaway.