The first volume of the Persona 4 manga has been released in the North American region. If you are interested, you can purchase the paperback from the Amazon shopping website with this link. You can also take a look at the cover of the first English volume of the series below this paragraph.
An enhanced port of the game, called Persona 4 Golden, was released for the PlayStation Vita on November 20, 2012. Several spin-off titles were also made, including Persona 4 Arena, Persona 4 Arena Ultimax, Persona Q: Shadow of the Labyrinth and the recently-released Persona 4: Dancing All Night.
Of course, Atlus is currently working on the long-awaited Persona 5, which features a new cast of characters when compared to Persona 4. The fifth mainline installment was first announced for the PlayStation 3 before being confirmed for the PlayStation 4. The upcoming title is currently slated for a summer release for both consoles in Japan after multiple delays.