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I saw a video like this one except it was very laggy. A few hours later, there was another video (same as the one in your post) where it was running super smooth.

It seems that Siri can be enabled on the iPhone 4. The real challenge now is whether or not they can get it to contact Apple's servers.
 
not surprised. i'm sure the jailbreakers will have it working on iphone 4's in no time.
 
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