[{"key":1,"version":1,"status":"ACTIVE","date":"Jan/10"},{"key":1,"version":2,"date":"Feb/10","status":"DRAFT"},{"key":2,"version":1,"date":"March/10","status":"ACTIVE"},{"key":3,"version":1,"date":"April/10","status":"ACTIVE"},{"key":3,"version":2,"date":"May/10","status":"ACTIVE"},{"key":3,"version":3,"date":"Jun/10","status":"DRAFT"}]

db.collection.aggregate([{"$sort":{"version":-1}},{"$group":{"_id":"$key","version":{"$first":"$version"},"date":{"$first":"$date"},"status":{"$first":"$status"}}},{"$project":{_id:0,key:"$_id",version:1,date:1,status:1}}])