Heard via NASASpaceFlight.com, the Hubble servicing mission (aka the only useful Shuttle flight on the manifest) has been moved up to the 10th of the remaining 17 flights:
The latest available Shuttle mission manifest continues to evolve ahead of an exciting finale for the three NASA orbiters, with the highlight mission of servicing the Hubble Space Telescope (HST) moving up to flight 10 of a 17 mission schedule.
HST-SM04 - STS-125 - has now moved from Endeavour to Discovery, with a new NET (No Earlier Than) launch date of April 11, 2008, moving ahead of STS-119 â€“ ISS Assembly flight 15A - from the previous manifest.
Still, two years is a long dang way off. Hubble is managing fairly well, but if it loses another gyro it's in trouble. If it loses a second one, it's unclear if it can be maintained in a stable attitude, meaning it might begin to tumble. That will make a Shuttle docking impossible, rendering moot all the fretting about servicing it. This is the biggest reason, in my mind, that we have to send a service mission to the Grand Lady sooner rather than later.