Jailbreak app developer Eric Day has released an app that brings Siri Dictation the iPhone 4. The app, titled “Siri0us,” is available now on Day’s Cydia repository here: http://apt.if0rce.com/
Please note that this is not a Siri port! Developers are still hard at work on the port, however. If you need some help installing Siri0us, then please refer to the video directly below.
UPDATE: We can confirm that Siri0us works on the iPod touch fourth generation! The developer’s servers are having some issues at the moment due to a high volume of traffic, so keep trying if you can’t get through.