Watch any of Apple’s recent iPhone 4S commercials and you’ll no doubt see a celebrity tapping and holding their phone’s Home button in to activate the (miraculously accurate) virtual assistant. But did you know that you can use Siri without hitting the Home button at all? Simply open up the Settings app, tap on General, tap on Siri, and turn Raise to Speak on. Now when you need help pulling together your gazpacho or answering ridiculously…