What you can't see, Steven, is that there's a corresponding hole under the nose but above the front wing - the two holes are connected right through the nose. That area beneath the nose is a high pressure zone so the channel through the nose acts as an extractor vent. Lower pressure under the nose means more downforce.
By carefully angling the flow through the upper hole, the aero boys can also ensure that it increases the downforce effects on rearward elements, particularly the rear wing. Patrick Head explained recently that this was what they were trying to achieve with the walrus nose Williams - except they went the whole hog and removed the bit of bodywork above the channel. Ferrari's solution looks better since the closed channel should enable the airflow to be better controlled.