Wow, there's a lot of iPhone users entrenched in their views of how something should work based on the way it's always been.
You have to remember that Apple isn't afraid to completely change their physical UIs. See iPod Shuffle, Nano, Touch, trackpads or many different attempts they've had had at mice (most of which are awful it has to be said).
Getting rid of the home button is a GREAT idea. Why?
1) they can use an on screen home icon that is always at the same location no matter which way up you're holding the iPhone/iPad.
2) they can change the home button graphic depending on context. If you're already in the home screen for example, it could become the task switch graphic.
For reference, there are already phones and tablets out there that have no home button. They work fine. eg. on the Nokia N900, 'home' is always the top left icon. It changes between an icon that goes back to the task switcher or if you're in task switcher already, to the new application launcher (which is kind of like iOS's app grids or 'home'). There are other UI paradigms on the N900 that are great but don't apply to iOS. The N900 runs a windowed UI instead of iOS's dumb fullscreen for everything paradigm. For instance, the N900 blurs out the background when you've a modal window in front. Clicking on the blur quits the current window. It's a little odd as windows often have no UI controls but no less odd than having to click 3 times on the home button or something equally daft.
To reset an n900, you hold the power button in for a long press and it pops up a menu asking what to do. This is the same as any Nokia for decades already and most other phones. The iPhone is the odd one out.
Voice commands with no button - just hold the 'call' virtual button in long enough. That's how Nokia does it on all their touch phones as well as letting you do it from the physical call button on phones that have them. The N900 is a bit odd here as it has no voice control at all, but then it's a tablet, not a phone really.