db = connect("localhost:27017/myTest");

print( "Prepareing test data" );
db.adminCommand( {enablesharding: "myTest"});
db.myColl.drop();
db.adminCommand( {shardcollection: "myTest.myColl", key: {key:1}} );
var padding = ''; for (var i=0; i<10000; i++){ padding += '*'; }
for (var i=0; i<5000; i++){ db.myColl.save({key: 0, value: i, padding: padding}); }

var conf = db.getSisterDB("config");
print( "Number of the shards : " + conf.shards.count() );
print( "Chunks : " );
conf.chunks.find({ns:"myTest.myColl"}).forEach(printjson);
print( "Test result:" );

for(var lm=100; lm<2000; lm+=100){
        var i=0;db.myColl.find().limit(lm).forEach(function(x){i=i+1});
        print(lm + ":" + i + (lm == i ? "" : " <- !?"))
}

$ mongo --nodb test.js
MongoDB shell version: 2.0.2
connecting to: localhost:27017/myTest
Prepareing test data
Number of the shards : 3
Chunks :
        "_id" : "myTest.myColl-key_MinKey",
        "lastmod" : {
                "t" : 1000,
                "i" : 0
        },
        "ns" : "myTest.myColl",
        "min" : {
                "key" : { $minKey : 1 }
        },
        "max" : {
                "key" : { $maxKey : 1 }
        },
        "shard" : "shard1" 
}
Test result:
100:100
200:115 <- !?
300:300
400:400
500:500
600:600
700:554 <- !?
800:454 <- !?
900:900
1000:1000
1100:1100
1200:993 <- !?
1300:893 <- !?
1400:793 <- !?
1500:1500
1600:1600
1700:1700
1800:1332 <- !?
1900:1232 <- !?