请注意，该版本还是在测试阶段，请勿在生产环境中使用。
下载地址：http://www.mongodb.org/downloads - Development Release (Unstable)
这里有一份关于 Upgrade MongoDB 2.2 to 2.4 指南。
MongoDB 2.4 的改变包括：
Text Indexes
New Modular Authentication System with Support for Kerberos
Role Based Access Control and New Privilege Documents
Default JavaScript Engine Switched to V8 from SpiderMonkey
Added Limitations for Map-Reduce and $where Operations
New Geospatial Indexes with GeoJSON and Improved Spherical Geometry
New Hashed Index and Sharding with a Hashed Shard Key
db.killOp() Can Now Kill Foreground Index Builds
$setOnInsert - New Update Operator
--setParameter Option Available on the mongos and mongod Command Line
来自:开源中国社区
