"auth":"0000000000000000000000000000","method":"maintenance.create","id":1,"params":{"hosts":[

],"description":"test","active_since":"1286576441","active_till":"1286590656","name":"test","maintenance_type":"0"},"jsonrpc":"2.0"

(with the auth obviously changed)gives an error

[ CMaintenance::create ] At least one host or group should be selected.

10052 definitely exists:

mysql> select hostid,host from hosts where hostid="10052";
-----------------------+

-----------------------+

-----------------------+
1 row in set (0.00 sec)

Also, I can't seem to specify the maintenance period, is this a feature request or a documentation bug?