Downloading metro stations of Paris from OpenStreetMap?

The OSM Wiki has instructions for downloading to different formats.

And here is some information about shapefiles.

Cloudmade has produced exports to different formats for France and can be found here.

One other approach is to use the Overpass javascript library to query the read-only OSM API. You can write a query that will select all of the relevant tags for an area. Here is an example from the wiki:

<bbox-query s="51.15" n="51.35" w="7.0" e="7.3"/>
<recurse type="node-way"/>
<query type="way">
  <item/>
  <has-kv k="highway" v="motorway"/>
</query>
<print/> 

To store the data in a more gis-friendly form you would probably need to parse it more but it seems like a quick way to access it.

One way to investigate this sort of thing is to use the "Export" tab on a sample area on the main OSM site.

If you export it as OSM XML, you will get a fairly large file, part of which will contain something like:

-<node version="12" timestamp="2012-10-29T00:16:52Z" changeset="13668746" visible="true" uid="158826" user="cquest" lon="2.3549579" lat="48.8460116" id="260040968">
   <tag v="Jussieu" k="name"/>
   <tag v="Jussieu" k="name:fr"/>
   <tag v="Жюссьё" k="name:ru"/>
   <tag v="station" k="railway"/>
   <tag v="1866" k="ref:FR:RATP"/>
   <tag v="1" k="STIF:zone"/>
   <tag v="metro" k="type:RATP"/>
   <tag v="no" k="wheelchair"/>
   <tag v="fr:Jussieu (métro de Paris)" k="wikipedia"/>
   <tag v="Жюссьё_(станция_метро)" k="wikipedia:ru"/>
 </node>

The key part is the station + railway part. If you export a large enough area (or use a pre-made export, as suggested by Fezter) and query for that tag, you should get every node that is a railway station. If you only want metro stations, then you might want to filter by other tags as well.