There are several cases where we have to define 3, 4,..,n Triggers for exactly the same situation,
only different Thresholds.
Triggers creation would get faster, cleaner and easier (and the Triggers view of an host would get less cumbersome)
if it was allowed to set these multiple severity levels in the same Trigger.

Maybe the Trigger expression builder could be revamped to further ease the configuration.

Use cases explained in both,
http://www.zabbix.com/forum/showthread.php?t=12003
http://www.zabbix.com/forum/showthread.php?p=79248