Well it appears a group of developers from Applidium were able to manage to run Siri on any device they wanted to use it on. The hackers were able to manipulate Siri by creating a fake returning address server and were able to get Siri to send commands there instead of directly back to the official Apple servers.
“It turns out Siri uses TCP to speak to a server at 18.104.22.168 using port 443. Applidium then logged on to a desktop computer, entered in that IP address, and realized that Apple was returning a server named “guzzoni.apple.com” and that Siri was using HTTPS as its protocol. Putting it simply, the group then created a fake guzzoni.apple.com address and tricked Siri into sending commands there instead of to Apple’s own server.” The hack has one big requirement, you have to have an iPhone 4S identifier to be able to use Siri on other devices. So it looks like the purchase of an iPhone 4S is ultimately the only way to get Siri. A set of tools on how to accomplish what the hackers were able to do is available at the link below.