I have to admit that Apple has mastered the marketing psychology of holding customers in suspense. I think its proven fact that an experience is enjoyed the more you delay or anticipate its occurrence. This is exactly what Apple is doing with the introduction of the iPad and establishing the pre-orders. Customers waited almost a month for the WiFi version and I have now waited more than a month for the WiFi 3G model which is not expected to arrive until late April.
The trick to Apple's magic is the introduction of occasional press releases or "leaks" regarding timing of deliveries to allow anticipation to build further. Regardless of how well the device will operate, once obtained anyone who waits 6-8 weeks for delivery will proudly use, showoff and display the device. The brand loyalty is enhanced.
One more week!