The beta includes two multiplayer maps: Chateau and the Airstrip (described here), both with "dynamic events" occurring during play, like planes flying in. Players can choose from nine modes including Team Deathmatch, 3-Team Deathmatch, Team Objective, Free For All, Plunder, High Stakes, and three unrevealed co-op modes that IGN mercilessly teased for a later reveal. Players will choose either a Drake/Sully/"treasure hunter" Hero team or a bad-guy team made up of customizable pirates.
Four of the new "Power Play" events will also feature in the beta. These one-minute events change the rules (like "marking" one person on the winning team to be worth three points) to turn the game around at critical moments.
Check IGN for the full rundown of beta components. The beta launches officially on July 4, but will be accessible early, on June 28, for Infamous 2 owners and PlayStation Plus members. Which, thanks to one of Sony's acts of contrition, will be everybody! As long as the store is back up by then, that is. The beta is set to end July 13.