As we’ve already reported, Square Enix will announce its plans for the Final Fantasy franchise at its September Anniversary Event next month, including its plans for the “Lightning Saga”, or the Final Fantasy XIII series. Though, in an interview in this week’s copy of Famitsu, it was revealed that the game has just now gone into production. The name of said title will officially be announced at the anniversary event on September 1st.
I haven’t played Final Fantasy XIII-2 myself, so I don’t know how good the game is. With this news, I can imagine that the game did well enough to get a sequel. That, or Square is being driven by some kind of mad hubris. Either scenario seems likely.
Source (http://andriasang NULL.com/con23o/ffxiii_title_announcement/)