Verified with recent Percona server 5.5.28 also:

...
mysql> explain partitions SELECT * FROM test_nico WHERE time_id >= '2012-10-09 00:00:00' AND time_id < '2012-10-16 00:00:00' AND cid = 'TpqiCvy6S9af5KbEL5fQ'\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: test_nico
   partitions: PM_2010_01_31,PM_2010_02_28,PM_2010_03_31,PM_2010_04_30,PM_2010_05_31,PM_2010_06_30,PM_2010_07_31,PM_2010_08_31,PM_2010_09_30,PM_2010_10_31,PM_2010_11_30,PM_2010_12_31,PM_2011_01_31,PM_2011_02_28,PM_2011_03_31,PM_2011_04_30,PM_2011_05_31,PM_2011_06_30,PM_2011_07_31,PM_2011_08_31,PM_2011_09_30,PM_2011_10_31,PM_2011_11_30,PM_2011_12_31,PM_2012_01_31,PM_2012_02_29,PM_2012_03_31,PM_2012_04_30,PM_2012_05_31,PM_2012_06_30,PM_2012_07_31,PM_2012_08_31,PM_2012_09_30,PM_2012_10_31,PM_2012_11_30,PM_2012_12_31
         type: ref
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 20
          ref: const
         rows: 36
        Extra: Using where; Using index
1 row in set (0.00 sec)

mysql> show variables like '%ver%';
+----------------------------------+------------------------------+
| Variable_name                    | Value                        |
+----------------------------------+------------------------------+
| character_set_server             | utf8                         |
| collation_server                 | utf8_unicode_ci              |
| innodb_force_recovery            | 0                            |
| innodb_recovery_stats            | OFF                          |
| innodb_recovery_update_relay_log | OFF                          |
| innodb_show_verbose_locks        | 0                            |
| innodb_version                   | 1.1.8-29.0                   |
| log_slow_verbosity               |                              |
| myisam_recover_options           | OFF                          |
| protocol_version                 | 10                           |
| relay_log_recovery               | OFF                          |
| rpl_recovery_rank                | 0                            |
| server_id                        | 0                            |
| slave_type_conversions           |                              |
| version                          | 5.5.28                       |
| version_comment                  | MySQL Community Server (GPL) |
| version_compile_machine          | x86_64                       |
| version_compile_os               | Linux                        |
+----------------------------------+------------------------------+
18 rows in set (0.00 sec)

mysql> show variables like 'char%';
+--------------------------+---------------------------------------+
| Variable_name            | Value                                 |
+--------------------------+---------------------------------------+
| character_set_client     | utf8                                  |
| character_set_connection | utf8                                  |
| character_set_database   | utf8                                  |
| character_set_filesystem | binary                                |
| character_set_results    | utf8                                  |
| character_set_server     | utf8                                  |
| character_set_system     | utf8                                  |
| character_sets_dir       | /home/openxs/dbs/p5.5/share/charsets/ |
+--------------------------+---------------------------------------+
8 rows in set (0.00 sec)