The Nike + iPod Sport Kit is not going to support the iPod itself. The Nike + iPod Sport Kit will only support the iPod nano. It's true. For all the countless regular iPod owners you won't be able to use the Sport Kit in all its goodness (well we'll see).
Here is my proof. First, if you go to the Nike + iPod Sport Kit website you can see that nowhere is there a mention of an iPod as a requirement. Only the iPod Nano. Also, today there was a new iPod Updater released (get it here). In the release notes there is a specific mention of only the iPod Nano getting "Nike + iPod support." All the iPod got were some bug fixes.
As more proof, I talked to 2 seperate Apple representatives at two separate Apple stores and they specifically told me that only the iPod Nano will be supported (sorry Shuffle). It seems that Apple has made it pretty clear to their retail employees that the Nike + iPod Sport Kit will only support the Nano. I asked one of the guys I talked to what the reason was. He told me that since the Nano is smaller, and Flash based so it is more ideally suited for running. The iPod is a hard-drive based player which (the Apple employee says) causes skipping and because of its size it wouldn't be suited for running. Personally, I have never experienced any skipping with my old 4th generation iPod (hard drive based) when running so I really don't see the logic behind Apple's thinking. Also, the new 5th generation iPod is pretty thin and even though it isn't as small as the Nano I still think it is a good small size.
So what am I (consumer) supposed to do? I've got the regular iPod and just bought the Sport Kit.
Well, you've really got three options. First, you can probably return it at the Apple Store; also since no one has gotten their kit yet (including you) you can probably cancel your online order.
Second, you can just receive your product and keep it hoping that someone creates a fix or Apple mends its ways and give you support for the kit. It can be determined that support for the kit is derived from the iPod updater because the Nano just had to receive an update which means that this is a software issue and nothing hardware. That means that someone could hack the software and give support for iPods. Also, most likely the guys that developed iPod Linux will hopefully develop support for the kit in an updated iPod Linux version.
Third, as soon as you get your kit you hoot and holler to Apple that there isn't support for the regular iPod and that you demand. Hopefully, everyone starts to go up-and-arms over this in the blogosphere and Apple listens. So for anyone reading this and has an iPod please call up Apple and request support for your iPod. Either now or when the Sport Kit first hits homes.