Even if you jailbreak your iPhone, even if you install some Super-Extra-Power-Magnum-MultiTask-Fovever 2.0 Limited Edition in your iPhone, even if you manage to obtain some sort of active dashboard in your iPhone, how many apps could you keep opened at the same time with 256MB of RAM and no virtual memory? And how long will your battery live?

You would just have a micro-wave cooker without any warranty.