How can I make a host show up by hostname in 'show processlist' rather than by IP address?
By default, MySQL makes a DNS lookup to resolve the client hostnames. You can disable this lookup with the option skip_name_resolve, check if your server wasn't started with this option:

[22:54:53] [DEV\(none)] mysql&gt; show variables like "skip_name_resolve";
+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| skip_name_resolve | ON    |
+-------------------+-------+
1 row in set (0.00 sec)


Best Regards,

Max.