I have implemented a map link demo at
http://test.wikipedia.org/wiki/Map_testing
This consists of about 10 lines of source code :-)
Format is [[map:laltitude:longitude]] or [[map:laltitude:longitude:zoom]]; if zoom is omitted, a default of 5 is used.
It can be switched to wiki-internal maps, once we have some. For the discussion about formats and stuff, see
http://meta.wikipedia.org/wiki/Wikipediatlas
Magnus
P.S.: I can't access sourceforge.net from the wikipedia server command line anymore, so I can't check in these changes myself.