First, they changed the shell. The Jot has a sleeker and more professional design than the original. It also has a slightly rough back so you can put it down without it sliding away from you. There's also a new stylus which doubles as a stand, as well as a replaceable battery and a save switch (protects against accidental erasure).
On the back are a couple magnets so you can hang it on the fridge. This will let it work like a message board. That makes excellent sense and I happen to know at least one person who has used the original Boogie Board for just that purpose.
This device is based on a proprietary Cholesteric LCD screen tech developed by Kent Display. The idea behind the Boogie Board is that you can write, draw, or scribble on it with a stylus or your finger. The screen will hold the contents without using electricity. When you're done writing, you click the erase button and the screen is cleared (this part requires electricity). It's something like a high tech etch-a-sketch.
The Jot is going to hit the market later this year with a retail of $40. That's about the same retail as the original Boogie Board, so it looks like they might be planning to replace one with the other.
I haven't had my hands on the Jot or the original Boogie Board but I did get to borrow the BB eWriter back in December. The eWriter uses the same screen as the Jot and it has one important feature that the Jot doesn't. The eWriter can save your notes as a PDF.