Looks like the day has finally come. Google made its announcement on the Today Show that Google Voice is starting to roll out invites to their backlog of users who reserved a number over the past 2 years. That has to be a huge backlog so I can imagine they will not be opening this to the public right away. I would highly advise getting yourself on the reservation list ASAP if possible.
Check your inbox if you signed up for a reservation before. I can only imagine that they will quickly run out of the 1 million numbers they reserved. It could change things when they open up number portability where you could port your number.
Here is to hoping you get your invite soon!