This just in, from Showtime:

"Showtime has ordered a second season of its freshman drama Dexter, starring Emmy- and Golden Globe-nominated actor Michael C. Hall, it was announced today by Robert Greenblatt, Showtime President of Entertainment. Dexter premiered last month to widespread critical acclaim and ranks as Showtime's top-rated series. Production is set to begin on 12 new episodes next spring [to] premiere on Showtime in late 2007."

New episodes of Dexter air Sundays at 10 pm/ET.