You have to wait until the package is given to the postal clerk for mailing before it will show up in tracking.

See below;

Label/Receipt Number: 0309 3220 0000 5867 1512
Expected Delivery Date: May 26, 2011
Class: Priority Mail®
Service(s): Delivery Confirmation™
Status: Processed through Sort Facility

Your item was processed through and left our PHILADELPHIA, PA 19116 facility on May 24, 2011 at 9:55 pm. The item is currently in transit to the destination. Information, if available, is updated periodically throughout the day. Please check again later.

Detailed Results:

Processed through Sort Facility, May 24, 2011, 9:55 pm, PHILADELPHIA, PA 19116
Acceptance, May 24, 2011, 2:51 pm, ABSECON, NJ 08201