One of the limitations of the iPhone 4S’s intelligent assistant Siri is its inability to speak your tweets into the iPhone‘s Twitter app. Here’s a quick workaround for that:
1. In your Mac or PC browser version of Twitter, you must first enable Twitter text messaging (if you've already done this, you can skip to step 5). Do this by clicking on the drop-down list on the top right (next to your twitter handle) and selecting Settings. Keep in mind that if you don't have unlimited texting, this could get expensive.