I am NOT encouraging you to pre-order Civilization IV, I swear. There's an extremely real possibility that this game will not be fun.
A while back I optimistically predicted that, given that Firaxis was pushing up the release date from November to October, the game must already be close to complete and would be free from the bugs and lack of polish that plagued Civ3. Some online research has cast doubt on that theory; an astute forum poster observed that Take 2 (which is publishing Civ4, and has recently caught a lot of flak over the various GTA controversies) ends its fiscal year on October 31. If the game ships before then, all the pre-orders and instant purchases will show up in this year's fiscal report; any time after then, it will count for next year's. Given this, it seems altogether plausible that the change in release date was pushed by the publisher, making it sadly possible that this game will be even more in need of patching.
Hope springs eternal in mine breast. If you're like me and obsessive about this stuff, you've probably already visited the two main fan sites. If you just want a quick preview, there are several early previews up.
Again, I strongly urge you to wait and see whether the game is good. Watch this space, I'll be sharing my impressions. However, if you've already made your mind up or know you'll be buying it anyways, you might consider pre-ordering. Doing this will give you a "free" pre-order package with some freebies like a music CD, spiral-bound manual, etc. You can find the cheapest price for the pre-order package over at Amazon; at 44.99, it's five bucks cheaper than anywhere else. You can also opt for free shipping if you don't mind waiting a while to receive it. However, the truly doomed may want to consider ordering from Gamestop. While priced at 49.99, you can get free OVERNIGHT shipping on this game if you enter the code "CIV1D" (without the quotes) when ordering the item. That means you'll most likely be playing it on the 24th or 25th. (Note that unlike movies and music, which have "Street Dates", games have "Ship Dates" and brick-and-mortar stores will not even receive the games until this date or later.)
I'm already planning my first game. I'm thinking of playing as Frederick of the Germans. I will build glorious cities that become the cultural center of the world, and seek to live in peace with all my neighbors.
UPDATE 10/17/05: If you were planning on ordering from Amazon, they just raised their price back up to 49.99. Fry's Outpost briefly had it for 36.99 (!) this weekend, but that also has been raised to the standard. I don't know if Take 2 is cracking down or they're feeling greedy. I imagine all existing orders will be honored at the sale price, but it has become less attractive to secure your order in advance. (As far as I know Gamestop is still offering free next-day shipping.)