Speed is in mph. A 3:15 marathon -my target- requires a speed of 8.06 mph. In '09 I ran a 3:22 or a speed of 7.78 mph average. In '10 I finished in 3:41 or 7.11 mph average.
The uphill sections on the course run from mile 16 to mile 21 or from Km 25.75 to 33.8. These are the slowest blocks in the '09 race. In '10 the 20-25 block is slower because I was forced to take a potty break losing several minutes there. After that the speed goes up a bit but then crashes on the last part, hovering around 6 mph as I was forced to walk more frequently and for longer stretches.