As we can see in these pictures Sauber have indeed prepared an F-Duct for testing in Australia. More details from the team are on Autosport.com (http://bit.ly/cSXnjh ). It seems the team are now more agile once again since they have shed the BMW ownership & management. Perhaps ex-McLaren test driver Pedro De La Rosa brought some ideas to the team
from the limited pcitures we have, we can see that the lefthand sidepod shoulder has an inlet mouded into it. this presumably feeds back through the sidepod and around theairbox to run int the shark fin. The ducting inside the sharkfin is quite evident and ends by connecting to the rear wing. it appears to attach to the mainplane (not the flap as with McLarens set up) somewhere behind the exisitng blown slot inlet.
From what we can see, it cannot becontrolled by the driver, so the duct may not be trying to do the same thing as the McLaren. Either the team rely on a a puely aerodynamic way to control the rear wing stalling, such as the duct choking at high speed and cutting off the flow the slot. Or the duct merely adds mass flow to the exisiting blown slot (raced in Bahrain) to allow the wing to be run even steeper and create yet more downforce. We will need mor eimages to be sure what Sauber are trying here.