Currently, the iPhone does not allow developers to
use background processes. Therefore, to fire alarms on the iPhone, you
can leverage Google Calendar in one of two ways:
1.You can set your Google Calendar account to send SMS text messages
for alarms. Any alarms you set on events in Pocket Informant will be
synced to your Google Calendar account and at the designated time, you
will receive an SMS text message as your alarm.
However if you are in Airplane mode or on an iPod Touch, you will not be able to receive these text messages.
2.Using the Google Calendar service, you can keep your internal phone
calendar and your Pocket Informant calendar in sync. By doing this, you
can then rely on the iPhone's built-in calendar alarms.
The quick start guide does a good job showing how to set either of these options up: http://download.pocketinformant.com/PIIP/PIIP_Quickstart.pdf