This feature never found its way into the final release unless you use Xcode and turn your iDevice into developer hardware. Now though, that’s not strictly true.
A new tweak is now available on jailbreak store Cydia that will enable the aforementioned multitouch gestures with the tap of a button.
You will, of course, need to have a jailbroken iPhone or iPod touch to install it. Follow our step by step guide posted here to jailbreak your iPhone, iPad or iPod touch with Redsn0w on iOS 4.3.1, or with PwnageTool 4.3, or with Sn0wbreeze on Windows if you haven’t already.
Simply download MT Gestures through the ModMyi repo and activate it inside WinterBoard.