Despite Apple flat-out stating that Siri will not be coming to older devices, enterprising developers have proven that the technology works on the iPhone 4, 3GS and iPad.

Now, iDownloadBlog is reporting that a new app called Siri0us is available for jailbroken iPhones that allows Siri-like voice dictation for those users who do not own an iPhone 4S.

Dictation works great on the iPhone 4, transcribing words into text rather quickly. The technology is actually Naunce-based dictation, but the end result is pretty much the same as Apple’s Siri. As you can see in the video, small ads are displayed in the bar above the mic icon. You will need an internet connection for the microphone to show up.

Siri0us is a Cydia app that completely bypasses Apple’s servers (a limiting factor in previous cracks) but still utilizes the Nuance engine on which Siri is based. Check out the video below to see Siri0us in action.