Lenders will begin coming out with price improvements now, some have already hit.

 Float until later in the day.  If the DOW holds under 200-250 range by the close, then additional reprices for the better could be coming.

There are economic reports tomorrow that can have an effect on interest rates, but they are of moderate importance.

Bid Price now on FNMA 6.0 coupon is at 101.18 right now.  Lenders haven't fully adjusted their pricing to reflect this yet.  If that holds steady tomorrow, keep floating.

Counterpoint: consider that the massive sell off in the DOW could be viewed by some as an over-reaction.  Any stock friendly news tomorrow could make the rubber band snap back.  Conservative play here is to lock tonight.