I was out chasing today too, although I have a different perspective of the storm John has described. His storm was actually my 2nd for the arvo. Having seen a few cells appear on radar I had a look out to the north west from the 28th floor of my building in the city and saw an impressive updraft that was producing a strong anvil. I dropped everything and left work (yeah I know!) at 2pm. After dashing home to get my camera and check the radar again I headed west towards Sunbury to intercept a larger storm which had been severe warned. I took my first few pics as I approached the storm. I noticed that a secondary updraft had formed under the anvil adjacent to the main updraft. There was also mammatus along the forward flank of the anvil. This storm was VERY slow moving so I even had time to take a call from Jimmy
After deciding that the storm was weakening I turned my attention to a new developing storm to the North East of Melbourne and I'm fairly certain this is the storm John was watching from Doncaster. The updraft was strong and capped with pileus (I think) as shown in my pics. From my perspective it looked like it was developing under the anvil of my first storm but due to the distance it was hard to tell.
I drove half an hour on the ring road and ended up in the north east outer Melbourne area of Kangaroo Ground where there is a lookout monument used by the Country Fire Authority for fire spotting. The view was impressive as the storm moved very slowly over the Ranges NE of Melbourne. There was a CFA volunteer with comms who was watching the progress of a lightning induced fire about 10km away in the mountains as shown in my pics. They were waiting for a water bomber chopper to arrive.
All in all it was a good show by Melbourne standards but unfortunately the storms did not persist into the evening.