Received an e-mail today that Maxis or EA is testing their servers. According to the e-mail, invitees will have access to the entire game for 4 or 5 hours tomorrow afternoon.
Sadly though, it looks as though the one hour time frame from the previous betas has been shortened. They are testing their servers and want to keep people running through or some nonsense like that. (again, according to the e-mail). It didn't say how long we'd have to play, if we could play more than one session in the allotted time, or anything like that. Just that this beta would allow access to the full version of the game rather than the closed off segments from the earlier betas.
If you pre-ordered the game, be sure to check your e-mail and see if you were invited to play as well! :)