It's being reported by Deadline that Syfy has ordered six episodes to wrap the series. This would be in addition to the thirteen episodes for Season Five currently being filmed (S4.5 is currently airing).
TVLine (pretty much the same thing)
However, James Hibbard at InsideTV has a somewhat different report. LINK
And here's TVbytheNumbers' take on it. LINK
What do you all think? I'm a little shocked, to be honest. After my initial "what?!?!?" reaction, I don't think I'd mind them planning ahead for a final season - that gives them a chance to give it a good ending if that's what they want. And while I love the show, I'd rather it end on a high note than otherwise. But I just don't get the six episode final season thing. Why not a full thirteen episode final season?