"half" the single player.
The second disc is therefore all single player. They also reaffirmed that the PC version has been "developed in parallel" to consoles, and it's "not a port." It releases in the middle of May.
Of course the PlayStation 3 copy of the game will be on a single Blu-Ray disc. Max Payne 3 releases on Xbox 360 and PS3 May 15th in the US, 18th in Europe. PC is May 29th.