I'll post this here. If your from the U.S. click this link and can see the forums you're in the beta and most likely just haven't received your email yet. If not it will say Access Denied.
http://community.us.playstation.com/t5/PlayStation-4-System-Software-4/bd-p/PS4_4_00_beta
I can see two threads. Guess i'm in. Just waiting on my code I suppose