There are a few caveats that come with this MMO resurrection. You have to be an active subscriber to Asheron's Call to take advantage of the AC2 server, and the game is currently in beta status, so there might be a few hiccups as Turbine figures things out.
Asheron's Call 2 came out in 2002 and was closed in 2005. Our Game Archaeologist column has a great retrospective to bring you up to speed if you're unfamiliar with this short-lived MMO.
[Thanks to Padre for the tip!]