I'm not sure if I understand your question correct.
If you mean: http://www.mediawiki.org/wiki/Maps_extension you should ask the creator Jeroen De Dauw directly.
If you only want to create a map you should check the possibilities of openlayers.org that we use for a lot of maps with multiple layers.
Greetings Kolossos
Am 27.07.2011 02:52, schrieb Christoph Holtermann:
have multiple Layers of Markers in the wikimedia Maps extension using openstreetmap ?
I would like to have a map where the user can enable two different layers of Markers. (working group locations and hospital locations).