The 0Z GFS has the upper system centered up at 40/62 (the big one at 500MB ) getting south enough...erroding the backside of the 588 high over Florida.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_000m.gif

This pops down the mid/upper high enough to release Gustav into the eastern Bahamas....then the ridge builds back to the east...trapping Gustav on a WNW track through the keys and into the SE Gulf.

I think...think this is a result of the GFS finally getting a handle on the initial intensity of Gustav (way too shallow before). I would initially write it off as a "bad run"...but if the other models start calling for an erosion of the EASTERN part of the high almost right away...then we could see some of the largest forecast errors in the last decade.