Where is Siri on my new iPhone 4S?

You can but it requires jailbreaking an iPod touch or iphone 4 on iOS 5. I you would like to get it you will have to wait a bit because there is only 1 website that tells you how to do it. But if you don't want to jailbreak your I device, there are some very similar apps on the app store for example "Vlingo" (it's quite good, although not as advanced as Siri), and Dragon Go , which I similar to Vlingo but has a different interface and does other things ( its still very similar to Vlingo though).