The Google Project Fi help center page is up
https://support.google.com/fi#topic=4596407
It talks about how it eliminates Google Voice once you subscribe. Good thing is you are able to move your google voice number to another email address if you want to keep it and not bring it to Project Fi or loose it.
I do find it odd that it's been +12 hours and only one user is reporting they received an invitation.
I was added to a friends and family list through a Google employee. I'm guessing those people get a somewhat higher priority. My phone was supposed to show up at work today, but FedEx never showed :'(
I have my phone. Now i'm just waiting for my current provider to complete the porting process.
Awesome. Definitely let us know how it's working out.