Same experience here in Florida. Two packages were supposed to be here yesterday(expected delivery date 6th) and one even said out for delivery. Neither came. I chased my mailman down and had him double check the boxes, nothing. He said there weren't any other mail trucks that they didn't work like that.
At night the tracking updated to say notice left. Nobody ever knocked, there was no notice. Called today and they said it should be at the local PO. Went there, they tell me it's out for delivery. They won't re attempt delivery after leaving a notice unless you request it.
I smell a plot afoot. There's something going on.
~defy
OK, I work for the PO so I'm going to try an explanation.

We have to scan all parcels when they arrive at our PO. Sometimes the parcel truck is late (after the carriers have left), or sometimes there are too many parcels for the carrier to be able to finish his route within 8 hours (no OT). So what happens to the parcel that was scanned "arrived at unit" that morning? The system (computerized) automatically adds "out for delivery" if a carrier hasn't done so by a preset time. It then also automatically adds a "notice left" if a carrier hasn't done one. The package, in all likelihood, has never left the building!
Chances are, your package is actually in your carrier's truck for delivery today.
Hope that helped!

JK