The new MacBook (and Pro) are the first notebooks from Apple to use a SATA optical drive. This opens the door to replacing the optical drive with a second hard drive.
There are at least six Liquid Submersion Indicators (LSIs) in the the MacBook. Don't feed coffee to your MacBook. Apple will know that you did.
No video adapters included in the box. Prepare to buy at least one US$30 video adapter if you expect to connect any type of monitor to the new MacBooks (except the new 24-inch LED Cinema Display, that is).
The keyboard is removable. If you're willing to remove 56 screws.
Hard drive swaps are now much easier in the MBP. The HDD sits next to the battery under a latched cover. The HDD is secured by one screw.
The Kensington lock prevents the bottom latch from being released, securing the battery, RAM and hard drive.
Two RAM slots support the 1066 MHz PC-8500 specification. Max chip density currently is 2GB for a total of 4GB. No word on 4GB chips.
Apple switched from using Intel to an NFORCE chipset on the motherboard. The serial ATA controller is an NVIDIA MCP79.
The glass front panel is bonded to the aluminum case behind the screen. If you bend the aluminum or break the glass fascia, you'll have to replace the entire screen and top case. It's one part.
System Preferences has new icons for Energy Saver and trackpad. (Shouldn't the CF bulb icon be white?)