Custom maps created with Bukkit.createMap() do not show the player position marker, even when using the default renderer.
NBT inspection of any map.dat file shows a parameter called trackingPosition. Maps generated by the game have this tag set to 1 and show the player marker on the map, Bukkit.createMap() maps have this tag set to 0 and do not show the marker.
I could really do with having access to a setTrackingPosition(boolean) method on mapView in order to turn the player position marker on for custom maps. Setting trackingPosition to 1 manually using an NBT editor adds the marker to my custom map next time I reload so I'm sure this is doable.