The iPad mini is delayed for two weeks at the Apple store, so if you want one, tough luck.
If you want the WiFi version of the iPad mini, you're going to have to wait. There's a two week delay on both the black and white version in the Apple store, the white one being placed on hold almost as soon as it was opened up for pre-orders on Friday. The tablet was set to be shipped this coming Friday, with the LTE version hitting the shelves next month.
The delay may simply have been caused by insufficient supply, or by extension, a particularly high demand. This is something analysts were quick to suggest as a possibility, after the device was announced last Tuesday. Another possible explanation is Hurricane Sandy, which is currently tearing up the east coast of the United States and may prohibit shipping. Apple has not released any statement officially explaining the reasons for the two week hold however, so one can only speculate.