After initializing a replica set every node that is added is set to primary.
This is the output for "rs.status()" from the "slaved" node (Also I added every other node from this one):
{
"set" : "rs0",
"date" : ISODate("2012-09-28T19:58:56Z"),
"myState" : 1,
"members" : [

{ "_id" : 0, "name" : "slaved:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "uptime" : 2144, "optime" : Timestamp(1348862047000, 1), "optimeDate" : ISODate("2012-09-28T19:54:07Z"), "self" : true }

,

{ "_id" : 1, "name" : "slavec:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "uptime" : 1052, "optime" : Timestamp(1348860655000, 1), "optimeDate" : ISODate("2012-09-28T19:30:55Z"), "lastHeartbeat" : ISODate("2012-09-28T19:58:55Z"), "pingMs" : 0 }

,

{ "_id" : 2, "name" : "slavee:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "uptime" : 637, "optime" : Timestamp(1348861573000, 1), "optimeDate" : ISODate("2012-09-28T19:46:13Z"), "lastHeartbeat" : ISODate("2012-09-28T19:58:55Z"), "pingMs" : 0 }

,

{ "_id" : 3, "name" : "master:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "uptime" : 289, "lastHeartbeat" : ISODate("2012-09-28T19:58:55Z"), "pingMs" : 0 }

],
"ok" : 1
}
(The last one is an arbiter). Also if I run rs.status() from every other node the only node listed is the self one.