One more thing. If you are clumsy, avoid the iPhone 4. Period. You WILL eventually drop it onto a corner and shatter that glass. It's not hard to change at ALL, but it can be annoying if you have a tendency to drop things. I baby all my electronics, so this hasn't been an issue for me.
You can get a big case for it that will protect it, but really, what's the point then? The thing is so awesome in your hand it would suck to cover it all up.
That being said, the Verizon iteration of the iPhone may correct some of the screen fragility.
cheers!