polifemo:
The U.S. Postal Service was electronically notified by the shipper on December 23, 2009 to expect your package for mailing. This does not indicate receipt by the USPS or the actual mailing date. Delivery status information will be provided if / when available. Information, if available, is updated periodically throughout the day. Please check again later.
USPS tracking is pretty much useless in this respect. Their claim of "updated throughout the day" is complete crap; if you're lucky they might update once before the package reaches you. If your package is actually lost, the tracking can be helpful (sometimes) in trying to figure out where it went astray.
Point is: nothing unusual in your experience with the USPS tracking service. The time it's taking for the package to reach you is probably just holiday season slowness.