There seems to be a bit of confusion over when CIV4 is going to be available.
According to the FIRAXIS website and many other sources, the release date was today, October 25. This is correct. However, that fact does not/did not mean that CIV4 would be universally available as of the release date.
In geographic locations, which are near distribution hubs, EB, Gamestop, Best Buy, etc., will most likely have the game on their shelves today (as of 12noon or later).
For all other locations, including much of the East coast, the game will have shiped today (from the previously mentioned distribution hubs) and will be in stores tomorrow, sometime during the day.
Had FIRAXIS/Take2 stated that October 25 was the 'street date' for CIV4, the game would have simultaneously been available throughout the country. In this instance, the game would have shipped last week from the distribution hubs to the stores/vendors. The vendors would hold the shipment in the back of the store until the street date. Vendors face monetary penalties for selling a 'street date' game prior to the time indicated by the publisher.
These same publishing tactics are present in many other media as well including movies and books.
It is definately aggrevating that this distinction was not (and is not) made more apparent. However, I hope this clears up the lingering confusion.