Dark Souls II, which is shaping up to be everything everything we could hope for from a sequel to Dark Souls, is currently in closed beta. Fortunately, if you didn't get in, the second wave of beta codes will be coming soon.
Like the first round of beta invites, Namco will distribute a single, universal code via their Facebook page. The first 30,000 people to redeem that code via the PS3 (or this site) will gain access to the network test. If you are unable to redeem the code, then unfortunately, you weren't quick enough.
Expect the code to be posted at 11 AM PDT this Thursday. On Saturday of this week, the servers will go live at 11 PM PDT, and will allow access to players from both waves of the Beta.
Since this is a beta, bugs can be expected and can be reported on the forms page of the official beta forum.
This particular beta is currently only open to North and South American players.