iOS (Jailbroken): One of the odd omissions in Siri is that you can’t tweet using it, even though Twitter is otherwise integrated into iOS. Sireet is jailbreak tweak that adds the ability to tweet natively from Siri to jailbroken devices.
The tweak works as you’d expect. After initiating Siri, you can say, “tweet” followed by your message and Siri will send your tweet directly to Twitter. It’s a free download for jailbroken devices and you can find it by searching for Sireet in the Modmyi repository.