The gang at "iFixIt' have torn down the iPhone 4. They say Apple definitely spent time giving the phone a thorough makeover, meticulously changing every little facet.
You can find the complete teardown at http://www.ifixit.com/Teardown/iPhone-4-Teardown/3130/1 . However, here are some of the highlights:
° Like the iPhone 3G and 3GS, there are two silver Phillips screws at the bottom of the phone. But removing these screws releases the rear case instead of the front glass, giving you immediate access to the battery.
° Unfortunately, the LCD panel is very securely glued to the glass and digitizer. If you break the glass, you'll have to replace the glass, digitizer, and LCD as a single assembly.
° The 3.7V, 1420 mAh Li-Polymer battery is not soldered in place, and very easy to remove.
° The iPhone 4 sports two cameras...| Read more »