[Update 6:30 p.m.] Regarding console exclusivity, a 2K spokesperson told Shacknews, "Currently The Betrayal of Jimmy is only available through the value pack." So the official word doesn't rule out eventually putting it up for sale, but for the time being the value pack seems like your best bet.
[Original Story] 2K Games announced a set of Mafia 2 "value-packed editions" today, and two of the three are already available. The game is getting a "Greatest Hits" release on PlayStation 3, and a "Platinum Hits" edition on Xbox 360, to match the systems' respective bargain branding. Both are hitting select retailers now for $29.99.
Each includes the game along with all of the associated downloadable content: the Betrayal of Jimmy, Jimmy's Vendetta, Joe's Adventures, and the four previously retail-exclusive Style Packs (Vegas, Renegade, Greaser, and War Hero).
A separate "Director's Cut" edition is slated to come out for the PC in the coming months for an undisclosed price. It will also include all of the DLC listed above. The Betrayal of Jimmy is of particular note, since until now the content was exclusive to the PlayStation 3.
We've sent a note to 2K to check if the Betrayal of Jimmy will now be available for sale separately on all platforms, or if Xbox 360 and PC owners can only get it through these value packs. We'll update as more information becomes available.