ESA's Christoph Steiger, Spacecraft Operations Manager at ESOC, provides this update today on GOCE fuel consumption.
Currently, the window for fuel depletion spans from now until 27 Oct. Our 'best guess' would be for early next week.
Some insight on the technical matters behind this: the pressure in the [spacecraft fuel] system is going to drop below the minimum operating pressure of the ion propulsion engine (2.5 bar) this Friday, after which the engine might continue working for a few more days.
Below 2.5 bar, the pressure everywhere in the system (high and low pressure section) will be the same, such that we can compare pressure measurements from various sensors, allowing us to judge the accuracy of the sole pressure sensor we're currently using. So in a few more days the picture should become much more clear.