In a surprising twist Director Kevin Greutert (who helmed Saw 6 and edited the previous Saw movies) has been hired by Paramount to direct Paranormal Activity 2! And Screenwriter Michael R. Perry will pen the script.
Oren Peli, who directed the first Paranormal Activity movie, is only producing the sequel. But no reason to worry according to him:
Paramount want to release Paranormal Activity on October 22, 2010 (yep, they really want to kill the Saw franchise!). So I think more details about the plot of Paranormal Activity 2 will surface online soon.