Last week, @chpwn and @stroughtonsmith released a video showing their Siri port on an iPhone 4 and iPod Touch. They used files from a jailbroken iPhone 4S, therefore they are currently not allowed to distribute the files because of copyright issues.
Today, @rpetrich, who released several tweaks like Activator or RetinaPad, got @chpwn’s and @stroughtonsmith’s port running on his iPhone 3GS. He is now working on Activator integration.
With Activator integration, Siri could do a lot of cool things it can’t do now, like opening Apps or changing Settings (ex. turn WiFi on/off). Together with HubotSiri, which adds custom commands to Siri, the functionality of Siri could be greatly increased.
However, to install Activator your iPhone needs to be jailbroken. So we will have to wait until we either have an iPhone 4S jailbreak or Siri on our iPhone 4.