I talk to my iPad 2 all the time, but it never answers me back. Still, there is a small kernel of hope that Siri may one day start chatting me up via my Apple tablet.
Apple's servers have their ears plugged and they're saying, "La, la, la, I can't hear you!" every time Siri tries to talk to them. The servers, you see, only recognize Siri when it's coming from an iPhone 4S.
We've already seen the same issue with porting Siri to older iPhones. Without an assist from the data servers, Siri is pretty much hobbled.
Developers are busy trying to come up a solution that will set Siri free on older devices. We'll keep you posted.